Angle Addition Problems

Answer Key - Grade 4 Math Worksheet

Write the answer on the line, or circle the answer.

1. 1.

   The whole angle measures 160°. One part measures 25°. What does the part marked ? measure?

   135
2. 2.

   A 170° angle is split into a 40° part and an unknown part, x. Which equation finds x?

   • 40 − x = 170
   • 170 − 40 = x
   • x − 40 = 170
   • 170 + 40 = x
3. 3.

   An angle is split into two parts of 40° and 50°. What does the whole angle measure?

   90
4. 4.

   A camera turns 105°. Then it turns 15° more in the same direction. How many degrees has it turned in all?

   120
5. 5.

   Two angles sit side by side on a straight line, so together they make 180°. One angle is 135°. What does the other angle measure?

   45
6. 6.

   The whole angle measures 80°. One part measures 35°. What does the part marked ? measure?

   45
7. 7.

   A 130° angle is split into a 35° part and an unknown part, x. Which equation finds x?

   • 35 − x = 130
   • x − 35 = 130
   • 130 + 35 = x
   • 35 + x = 130
8. 8.

   A sprinkler turns 90°. Then it turns 40° more in the same direction. How many degrees has it turned in all?

   130
9. 9.

   An angle is split into two parts of 130° and 20°. What does the whole angle measure?

   150
10. 10.

    Two angles sit side by side on a straight line, so together they make 180°. One angle is 150°. What does the other angle measure?

    30