Question

find a number whose 80% is 12​

Answer 1

Let the number be x
80% of x= 12
Now transfer 80% to rhs
x = 12*100/80
= 3*5
=15

Answer 2

$\frac{12}{x } \times 100 = 80 \\ \frac{1}{x } = \frac{80}{100 \times 12 } \\ \frac{1}{x} = \frac{1}{15} \\ x = 15$

thanks..............