Let’s solve each problem one by one. Remember: angles on a straight line add up to
180°. That’s the key rule here!
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Problem 1:
We see three angles on a straight line:
- One is labeled
x°
- Another is
40°
- The third is
60°
So, we write:
x + 40 + 60 = 180
Add 40 and 60 → that’s 100
So:
x + 100 = 180
Subtract 100 from both sides:
x = 80
✔ Check: 80 + 40 + 60 = 180 → Correct!
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Problem 2:
Angles on the straight line:
-
x°
-
62°
-
57°
Equation:
x + 62 + 57 = 180
Add 62 + 57 → that’s 119
So:
x + 119 = 180
Subtract 119:
x = 61
✔ Check: 61 + 62 + 57 = 180 → Correct!
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Problem 3:
Angles:
-
x°
-
44°
-
x° (again — same variable!)
So:
x + 44 + x = 180
Combine like terms:
2x + 44 = 180
Subtract 44 from both sides:
2x = 136
Divide by 2:
x = 68
✔ Check: 68 + 44 + 68 = 180 → Correct!
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Problem 4:
Angles:
-
x°
-
19°
-
22°
-
30°
Add them all:
x + 19 + 22 + 30 = 180
Add the numbers: 19 + 22 = 41; 41 + 30 = 71
So:
x + 71 = 180
Subtract 71:
x = 109
✔ Check: 109 + 19 + 22 + 30 = 180 → Correct!
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Problem 5:
Angles:
-
x°
-
43°
-
x°
-
52°
Equation:
x + 43 + x + 52 = 180
Combine:
2x + 95 = 180
Subtract 95:
2x = 85
Divide by 2:
x = 42.5
✔ Check: 42.5 + 43 + 42.5 + 52 = 180 → Yes! (42.5 + 42.5 = 85; 85 + 43 = 128; 128 + 52 = 180)
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Problem 6:
Angles:
-
x°
-
61°
-
108°
Wait — let’s look carefully. Are these all on the same straight line?
Yes — they are adjacent angles forming a straight line.
So:
x + 61 + 108 = 180
Add 61 + 108 = 169
So:
x + 169 = 180
Subtract 169:
x = 11
✔ Check: 11 + 61 + 108 = 180 → Correct!
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Final Answer:
1) x = 80
2) x = 61
3) x = 68
4) x = 109
5) x = 42.5
6) x = 11
Parent Tip: Review the logic above to help your child master the concept of find the missing angle worksheet.
