Nathan B. answered 09/28/16
Tutor
5
(20)
Elementary and Algebraic skilled
Here's what we know:
a + b + c = 180 (triangle angles add up to 180)
b = 5a (the second angle is five times the first)
c = b + 81 (the third is 81 more than the second)
Plug in the variables:
a + 5a + b + 81 = 180
a + 5a + 5a + 81 = 180
simplify:
11a + 81 = 180
Subtract 81:
11a = 99
Divide by 11:
a = 9
b = 5 * 9
b = 45
c = 45 + 81
c = 126
Check:
9 + 45 + 126 = 180
180 = 180