Question

31,50 is 42% os what number

Answer 1

$\frac{31,50}{x}=\frac{42}{100}$

The right fraction represents the percentage; 42 over 100 (100 is the total), or 0.42.
The left fraction is the part number over the whole number. The whole number is unknown, so we use 'x'.


$\frac{31.50}{x} = \frac{42}{100}\\\\cross\ multiply\\\\31.50\times100=3150\\42\times x=42x\\\\3150=42x\\x=75$
Your answer is 75.