A percentage is simply a fraction in terms of a hundred, i.e. we get the ratio in terms of a denominator of 100%.
a.
To get the value of the whole number to which 52 is 65% of, we have:
[tex]\begin{gathered} \frac{52}{x}\times100\text{ \%=65\%} \\ \text{ We multiply both sides by x to get} \\ 5200=65x \\ \text{ Divide both sides by 65 to get:} \\ x=\frac{5200}{65}=80 \end{gathered}[/tex]52 is 65% of 80
b.
85% of 40 can be easily gotten as:
[tex]\frac{85}{100}\times40=34[/tex]85% of 40 is 34