Answer:
39
Step-by-step explanation:
the equation is:
4x - 15 + x = 180
4x + x - 15 = 180
5x - 15 = 180
+15 = +15
5x - 0 = 195
5x/5 = 195/5
x = 39
(4x - 15) + x
(4(39) - 15) + 39
(195 - 15) + 39
141 + 39
180
A circle has 360 degrees but in the problem you are using half of it. You 180 that's why the whole equations has to equal 180 to be right.
