500
A rectangle with sides measuring x-1 and x+3 has the same perimeter as a triangle with sides measuring x+1, x+3, and x+5. What is the perimeter?
2(x - 1 + x + 3) = x + 1 + x + 3 + x + 5
2x + -2 + 2x + 6 = 3x + 9
4x + 4 = 3x + 9
1x + 4 = 9
x = 5
2(5 - 1 + 5 + 3) = 5 + 1 + 5 + 3 + 5 + 5
2(12) = 24
24 = 24
The perimeter is 24