ab^2 =27/5 (1)
a^2b = 135 (2) divide (2) by (1)
a/b = 135 / (27/5)
a/b = 25
a = 25b sub this into (2) for a
(25b)^2 * b = 135
625 b^3 = 135
b^3 = 135/625 = 27/125 take the cube root of both sides
b= 3/5
And a = 25(3/5) = 15
So
a + 5b =
15 + 5(3/5) =
15 + 3 =
18