Assuming you really mean √(24/125). This is equivalent to √24/√125

√24 = √[4(6)] = (√4)(√6) = 2(√6)

√125 = √[25(5)] = (√25)(√5) = 5(√5)

So we now have 2(√6)/[5(√5)]

Generally, you would rationalize the denominator by multiplying both numerator and denominator of this fraction by √5.

We then have 2√30/25

√24 = √(4 • 6) = √4√6 = 2√6

√125 = √(25 • 5) = √25√5 = 5√5