You can use the pythagorean theorem. Now lets write out what we know.
Shorter leg = x Longer Leg = x + 7 Hypotenuse = x - 7
Now solve for x x = 28 Since you know x = 28, which is the shorter leg, you can solve for the rest by just plugging in 28 where x is located. For instance, longer let is x + 7 so 28 + 7 = 35