Answer
$28$
Work Step by Step
Before multiplying the fractions, cancel common factors first to obtain:
$\require{cancel}
=\dfrac{\cancel{21}^7}{\cancel{25}} \cdot \dfrac{\cancel{100}^4}{\cancel{3}}
\\=\dfrac{7(4)}{1(1)}
\\=\dfrac{28}{1}
\\=28$