Question

100/x * 40 = 20, x= ?

Answer 1

$\frac{100}{x} \times 40 = 20 \\ \\ \frac{100 \times 40}{x} = 20 \\ \\ \frac{4000}{x} = 20 \\ \\ 20 \times x = 4000 \\ \\ x = 200$

Answer 2

100 / x * 40 = 20 ⇒ 20 x = 40 * 100 ⇒ x = 4 000 / 20 ⇒ x = 200