Question

find a number whose fifth part is increased by 30 is equal to its fourth part decreased by 30

Answer 1

let no. be x
$\frac{x}{5} + 30 = \frac{x}{4} - 30$
$30 + 30 = \frac{x}{4} - \frac{x}{5}$
$60 = \frac{5x - 4x}{20}$
$60 = \frac{x}{20}$
$x = 60 \times 20$
$x = 120$