So this... is a slightly complicated problem you have to set up an equation.... so 7x-12=2x+8 you subtract 2x and add 12 to both side so now you have 5x=20 now divide both sides by 5 now you have x= 4 so plug it into the problems for the sides 2(4)+8= 14 is the length of one side and 7(4)-12=16 so 16 is the length for the other now you just pick the measurement to use hope this helped!!!!! have an amazing day!