Students practice calculating total earnings and time worked through real-world scenarios like babysitting and lawn mowing.

Let's solve each problem step by step:

---

Problem 1:

Pete is paid 50 cents a day to take out the trash and feed the dog. How much will he earn in four weeks?

- Step 1: Calculate the number of days in four weeks.
\[
4 \text{ weeks} \times 7 \text{ days/week} = 28 \text{ days}
\]

- Step 2: Calculate Pete's daily earnings.
\[
50 \text{ cents/day} = 0.50 \text{ dollars/day}
\]

- Step 3: Calculate Pete's total earnings over 28 days.
\[
0.50 \text{ dollars/day} \times 28 \text{ days} = 14 \text{ dollars}
\]

- Answer:
\[
\boxed{14}
\]

---

Problem 2:

Sally receives $5.00 a week for allowance. She is saving to buy a pair of roller blades that cost $45.00. How many weeks must she save?

- Step 1: Determine how much Sally saves per week.
\[
\$5.00 \text{ per week}
\]

- Step 2: Calculate the total amount Sally needs to save.
\[
\$45.00
\]

- Step 3: Divide the total cost by her weekly savings to find the number of weeks.
\[
\frac{45.00}{5.00} = 9 \text{ weeks}
\]

- Answer:
\[
\boxed{9}
\]

---

Problem 3:

Nancy earns $2.00 an hour babysitting. She babysat on Saturday from 7:00 p.m. to 11:30 p.m. How much did she earn?

- Step 1: Calculate the total time Nancy babysat.
\[
11:30 \text{ p.m.} - 7:00 \text{ p.m.} = 4 \text{ hours and } 30 \text{ minutes}
\]
Convert 30 minutes to hours:
\[
30 \text{ minutes} = 0.5 \text{ hours}
\]
So, total time:
\[
4 + 0.5 = 4.5 \text{ hours}
\]

- Step 2: Calculate Nancy's earnings.
\[
4.5 \text{ hours} \times \$2.00/\text{hour} = \$9.00
\]

- Answer:
\[
\boxed{9}
\]

---

Problem 4:

Dennis mows and trims lawns for $3.50 an hour. It took him 3 hours to do Mr. Wilson's lawn. How much did he earn?

- Step 1: Calculate Dennis's hourly rate.
\[
\$3.50/\text{hour}
\]

- Step 2: Calculate the total time spent.
\[
3 \text{ hours}
\]

- Step 3: Calculate Dennis's earnings.
\[
3 \text{ hours} \times \$3.50/\text{hour} = \$10.50
\]

- Answer:
\[
\boxed{10.50}
\]

---

Problem 5:

Bart delivers 180 newspapers in 3 hours. How many papers an hour does he deliver?

- Step 1: Calculate the total number of newspapers delivered.
\[
180 \text{ newspapers}
\]

- Step 2: Calculate the total time spent.
\[
3 \text{ hours}
\]

- Step 3: Calculate the number of newspapers delivered per hour.
\[
\frac{180 \text{ newspapers}}{3 \text{ hours}} = 60 \text{ newspapers/hour}
\]

- Answer:
\[
\boxed{60}
\]

---

Problem 6:

Eric earns two cents for each paper he delivers. He delivers 75 papers a day, 7 days a week. How much will Eric earn in a week?

- Step 1: Calculate Eric's daily earnings.
\[
75 \text{ papers/day} \times 2 \text{ cents/paper} = 150 \text{ cents/day}
\]
Convert cents to dollars:
\[
150 \text{ cents} = 1.50 \text{ dollars}
\]

- Step 2: Calculate Eric's weekly earnings.
\[
1.50 \text{ dollars/day} \times 7 \text{ days/week} = 10.50 \text{ dollars/week}
\]

- Answer:
\[
\boxed{10.50}
\]

---

Problem 7:

Liz earned $12.00, $7.50, $3.50, and $9.00 babysitting. She charges $2.00 an hour. How many hours did Liz babysit?

- Step 1: Calculate Liz's total earnings.
\[
12.00 + 7.50 + 3.50 + 9.00 = 32.00 \text{ dollars}
\]

- Step 2: Calculate Liz's hourly rate.
\[
\$2.00/\text{hour}
\]

- Step 3: Calculate the total hours Liz babysat.
\[
\frac{32.00 \text{ dollars}}{2.00 \text{ dollars/hour}} = 16 \text{ hours}
\]

- Answer:
\[
\boxed{16}
\]

---

Problem 8:

Josh earns $2.00 an hour for yard work and $1.00 an hour for walking the neighbor's dog. This week, Josh did 8 hours of yard work and walked the dog 3½ hours. How much did Josh earn altogether?

- Step 1: Calculate Josh's earnings from yard work.
\[
8 \text{ hours} \times \$2.00/\text{hour} = \$16.00
\]

- Step 2: Calculate Josh's earnings from walking the dog.
\[
3.5 \text{ hours} \times \$1.00/\text{hour} = \$3.50
\]

- Step 3: Calculate Josh's total earnings.
\[
16.00 + 3.50 = 19.50 \text{ dollars}
\]

- Answer:
\[
\boxed{19.50}
\]

---

Final Answers:

1. \(\boxed{14}\)
2. \(\boxed{9}\)
3. \(\boxed{9}\)
4. \(\boxed{10.50}\)
5. \(\boxed{60}\)
6. \(\boxed{10.50}\)
7. \(\boxed{16}\)
8. \(\boxed{19.50}\)