The triangle has 3 sides: a, b, c
The perimeter of the triangle is 79.75 inches: → a + b + c = 79.75
The second side of the triangle is half as big as the first side: → b = a/2
The third side is 7.25 inches greater than the first side: → c = a + 7.25
a + b + c = 79.75 → but you know that: c = a + 7.25
a + b + (a + 7.25) = 79.75
a + b + a + 7.25 = 79.75
2a + b = 79.75 - 7.25
2a + b = 72.5 → but you know that: b = a/2
2a + (a/2) = 72.5
(4a/2) + (a/2) = 72.5
(4a + a)/2 = 72.5
5a/2 = 72.5
5a = 2 * 72.5
a = (2 * 72.5)/5
→ a = 29
b = a/2
b = 29/2
→ b = 14.5
c = a + 7.25
c = 29 + 7.25
→ c = 36.25