4 is greate than -4 so the second portion becomes ab(4) = 3120
-4 is for the first part a/b (-4) = -60/13
4 ab = 3120
ab = 780
b = 780/a
-4 a/b = -60/13
-4a / (780/a) = -60/13
a^2 / 195 = 60/13
a = sqrt [ 60(195)/13] = 30 then b = 780/30=26 you can finish .......
