algebra
posted by Jessica .
One side of a triangle is half the longest side. The third side is 9 meters less than the longest side. The perimeter is 61 meters. Find all three sides.

c = the longest side
a = c / 2
b = c  9
P = a + b + c = 61 m
a + b + c = 61
c / 2 + c  9 + c = 61 Multiply both sides by 2
c + 2 c  18 + 2 c = 122
5 c  18 = 122
5 c = 122 + 18
5 c = 140 Divide both sides by 5
c = 140 / 5
c = 28 m
a = c / 2
a = 28 / 2
a = 14 m
b = c  9
b = 28  9
b = 19 m