Question

How to solve 5 by 7 into x by 5 is equals to 3 by 1?

Answer 1

Given,
$\frac{5}{7} \times \frac{x}{5} = \frac{3}{1} \\ \frac{x}{7} = 3 \\ x = 3 \times 7 = 21$

Answer 2

(5×X)÷(7×5)=3 X=3×7=21