We have,
(5t2)2÷(25t)3/2×(5t1/2)3
⇒(52t4)÷(52t)3/2×(5t1/2)3
⇒(52t4)÷(53t3/2)×(53t3/2)
⇒(52t4)÷(56t3)
⇒5−4t
So, the power of t is 1.
Hence, this is the answer.