All straight lines measure 180 degrees. In the diagram below, the straight line EF contains three angles, < 3, <4, and <5. If <3 is 90 degrees. What is the measurement of <4 + <5 = _________?

Question

A. 180 degrees

B. 90 degrees

C. 45 degrees

Answer 1

This requires a diagram.

Assuming that < 3, <4, and <5 are adjacent and together form a straight angle along EF,

<3 + <4 + <5 = 180
But, <3 = 90
=> 90 + <4 + <5 = 180
=> <4 + <5 = 180 - 90 = 90