Question

How do u solve 31 is 40% of what number? So confused?

Answer 1

`Method\ \#1\\\\\begin{array}{ccc}31&-&40\%\\x&-&100\%\end{array}\ \ \ \ |cross\ multiply\\\\\\40x=31\cdot100\ \ \ \ |divide\ both\ sides\ by\ 40\\\\x=(3100)/(40)\\\\\boxed{x=77.5}`


`Method\ \#2\\\\p\%=(p)/(100)\to40\%=(40)/(100)=0.40=0.4\\\\x-the\ number\\\\40\%\ of\ the\ number\ is\ 31:\\\\0.4x=31\ \ \ \ |divide\ both\ sides\ by\ 0.4\\\boxed{x=77.5}`