Raymond B. answered 11/21/20
Math, microeconomics or criminal justice
15^2 = 225
225 = S^2 + (S+3)^2 = 2S^2 + 6S + 9
rearrange terms and solve the quadratic for S, the smaller leg
S^2 + S^2 + 6S + 9 = 225
2S^2 + 6S - 116 = 0
factor or use the quadratic formula
Or much faster & easier is to recognize this is a 3-4-5 right triangle, inflated by a factor of 3, so
it's a 9-12- 15 triangle, with 2 sides 9 and 12, one 3 more than the other
15^2 = 12^2 + 9^2
225 = 144 + 81 = 225