Question

12i is 80% of what number

Answer 1

$\frac{80}{100} = \frac{12}{x}$

then you cross multiply which gets you

$1200 = 80x$

then you divide bot sides by 80

$\frac{1200}{80} = \frac{80x}{80}$

which gets you to 

15 = x

Answer 2

$\frac{80}{100} = \frac{12}{x}$