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Grade 7 · Math

Complete a straight angle

Use the 180-degree sum of adjacent angles on a straight line.

8 generated examples + worked example

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Worked example

Adjacent angles form a line. One is 65°. What is the other?

Answer & why

Answer: 115

180 − 65 = 115 degrees.

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Try these examples

8 reproducible examples from this math generator. Choose New examples for another set.

Question 1

Two angles form a straight angle of 180°. One measures 140°. How many degrees is the other?

  1. 40
  2. 30
  3. 80
  4. 50
A hint

Subtract the known angle from 180 degrees.

Answer & why

Answer: 40

Angles on a straight line total 180°. 180 − 140 = 40°.

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Question 2

Two angles form a straight angle of 180°. One measures 80°. How many degrees is the other?

  1. 80
  2. 100
  3. 110
  4. 90
A hint

Subtract the known angle from 180 degrees.

Answer & why

Answer: 100

Angles on a straight line total 180°. 180 − 80 = 100°.

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Question 3

Two angles form a straight angle of 180°. One measures 100°. How many degrees is the other?

  1. 80
  2. 60
  3. 100
  4. 120
A hint

Subtract the known angle from 180 degrees.

Answer & why

Answer: 80

Angles on a straight line total 180°. 180 − 100 = 80°.

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Question 4

Two angles form a straight angle of 180°. One measures 50°. How many degrees is the other?

  1. 130
  2. 150
  3. 110
  4. 120
A hint

Subtract the known angle from 180 degrees.

Answer & why

Answer: 130

Angles on a straight line total 180°. 180 − 50 = 130°.

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Question 5

Two angles form a straight angle of 180°. One measures 120°. How many degrees is the other?

  1. 60
  2. 90
  3. 50
  4. 70
A hint

Subtract the known angle from 180 degrees.

Answer & why

Answer: 60

Angles on a straight line total 180°. 180 − 120 = 60°.

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Question 6

Two angles form a straight angle of 180°. One measures 70°. How many degrees is the other?

  1. 90
  2. 150
  3. 120
  4. 110
A hint

Subtract the known angle from 180 degrees.

Answer & why

Answer: 110

Angles on a straight line total 180°. 180 − 70 = 110°.

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Question 7

Two angles form a straight angle of 180°. One measures 60°. How many degrees is the other?

  1. 160
  2. 120
  3. 110
  4. 130
A hint

Subtract the known angle from 180 degrees.

Answer & why

Answer: 120

Angles on a straight line total 180°. 180 − 60 = 120°.

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Question 8

Two angles form a straight angle of 180°. One measures 90°. How many degrees is the other?

  1. 110
  2. 120
  3. 90
  4. 80
A hint

Subtract the known angle from 180 degrees.

Answer & why

Answer: 90

Angles on a straight line total 180°. 180 − 90 = 90°.

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