Firstly we have to find the prime factors of 125
125 = 5 × 5 × 5
And the prime factors of 64
64 = 2 × 2 × 2 × 2 × 2 × 2
\(\sqrt[3]{(125 × 64) }\)
= \(\sqrt[3]{(5 × 5 × 5 × 4 × 4 × 4) }\)
= \(\sqrt[3]{ (5 × 5 × 5) }\)× \(\sqrt[3]{ (4 × 4 × 4) }\)
= 5 × 4 = 20
∴ 20 is the correct answer.