Question

Find two numbers such that one is 5 times the other and their differnce is 20.

Answer 1

that two number are

X and 5X

difference

5X - X = 20

4X = 20

X = 20/4

X = 5

hence two number are

5 and 25

Answer 2

let alpha and beta be the two numbers
$\alpha = 5 \: \beta .......{eqn1}$
$\alpha - \beta = 20$
$5 \beta - \beta = 20.........from \: eqn1$
$4 \beta = 20$
$\beta = 20 \div 4$
$\beta = 5$
$put\beta = 5 \: in \: eqn1$
$\alpha = 5 \: \beta$
$\alpha = 5 \times 5$
$\alpha = 25$