Answer with Explanation:

Let (25)7.5 x (5)2.5 ÷ (125)1.5 = 5x.

Then, (52)7.5 x (5)2.5/(53)1.5 = 5x 

=>  5(2 x 7.5) x 52.5 / 5(3 x 1.5) = 5x

=>  515 x 52.5 / 54.5  = 5x 

=> 5x = 5(15 + 2.5 - 4.5)

=>5 raised to x = 5 raised to 13

Therefore x=13