Writing Algebraic Expressions Worksheets - Math Monks - Free Printable

Let's solve each problem step by step and write the corresponding algebraic expressions.

---

Problem 1:

Mr Swann had \( x \) students in his class. One day 4 students left and the very next day 8 students joined. How many students are now present in his class?

#### Solution:
1. Initially, Mr Swann had \( x \) students.
2. On the first day, 4 students left. So the number of students became:
\[
x - 4
\]
3. On the next day, 8 students joined. So the number of students became:
\[
(x - 4) + 8
\]
4. Simplify the expression:
\[
x - 4 + 8 = x + 4
\]

#### Final Answer:
\[
\boxed{x + 4}
\]

---

Problem 2:

Amelia had 18 needles in her sewing box. She lost \( p \) of them. How many needles are still left with her?

#### Solution:
1. Initially, Amelia had 18 needles.
2. She lost \( p \) needles. So the number of needles left is:
\[
18 - p
\]

#### Final Answer:
\[
\boxed{18 - p}
\]

---

Problem 3:

In a zoo, there are \( z \) number of lions. \(\frac{3}{5}\) of the lions are male. How many of them are male lions?

#### Solution:
1. The total number of lions is \( z \).
2. \(\frac{3}{5}\) of the lions are male. So the number of male lions is:
\[
\frac{3}{5} \times z = \frac{3z}{5}
\]

#### Final Answer:
\[
\boxed{\frac{3z}{5}}
\]

---

Problem 4:

The total distance between your house and the school is 28 km. Starting from your house, what is the distance left to be covered if you have already covered \( x \) km?

#### Solution:
1. The total distance between the house and the school is 28 km.
2. You have already covered \( x \) km. So the distance left to be covered is:
\[
28 - x
\]

#### Final Answer:
\[
\boxed{28 - x}
\]

---

Problem 5:

Two-fifth of a certain number when decreased by 5 gives you the result you desire. Write an expression for the same.

#### Solution:
1. Let the certain number be \( n \).
2. Two-fifth of the number is:
\[
\frac{2}{5} \times n = \frac{2n}{5}
\]
3. When this value is decreased by 5, the expression becomes:
\[
\frac{2n}{5} - 5
\]

#### Final Answer:
\[
\boxed{\frac{2n}{5} - 5}
\]

---

Final Answers:

1. \(\boxed{x + 4}\)
2. \(\boxed{18 - p}\)
3. \(\boxed{\frac{3z}{5}}\)
4. \(\boxed{28 - x}\)
5. \(\boxed{\frac{2n}{5} - 5}\)