Answer
$2\frac{3}{16}$
Work Step by Step
$\frac{25}{40}\div\frac{10}{35}$
= $\frac{25}{40}\times\frac{35}{10}$ (division of factors i.e. multiply by the reciprocal of the second factor)
= $\frac{5\times5}{2\times2\times2\times5}\times\frac{5\times7}{2\times5}$ (representing as prime factorization)
= $\frac{1\times5}{2\times2\times2\times1}\times\frac{1\times7}{2\times1}$
= $\frac{5\times7}{2\times2\times2\times2}$
= $\frac{35}{16}$
= $2\frac{3}{16}$