Hello from MrBillDoesMath!
Answer:
c= 42.5
Discussion:
In the attachment, L is the longest side of the right triangle and "c" is its hypotenuse. The Pythagorean theorem gives
20^2 + L^2 = c^2 => as 20^2 = 400 and c = L+5
400+ L^2 = (L+5)^2 => (L+5)^2 = L^2 + 10L + 25
400 + L^2 = L^2 + 10L + 24 => subtract L^2 from both sides
400 = 10L + 25 => subtract 25 from both sides
400 -25 = 10L =>
375 = 10L =>
L = 375/1- = 37.5
Hence c = L + 5 = 37.5 +5 = 42.5
Thank you,
MrB