Question

if 40% of a number is 36 what will be 15% of that number

Answer 1

let the number be x
then
$\frac{40}{100} \times x = 36 \\ x = \frac{3600}{40 } \\ x = 90 \\ \\ now \: 15\% \: of \: x = \\ \frac{15}{100} \times 90 = 13.5$

Answer 2

40/100*x=36

x=90

15% of x=15/100*90 = 13.5