x = length of shorter leg (a)
x+4 = length of longer leg (b)
2x-4 = length of the hypotenuse (c)
a2 + b2 =c2
(x)2 +(x+4)2 =(2x-4)2
x2 +x2 +8x+16 = 4x2 -16x+16
2x2 -24x = 0
x(x-12)=0
x = 0 or x=12
the length of a side of a triangle can not equal 0, so x=12
12 is the length of the shorter leg
check
122 +162 =202
144+256=400
400=400 true
12 is the length of the shortest leg