Question

40% of what number is 34?

Answer 1

x - the number

$40\% x=34 \\ \frac{40}{100}x=34 \\ \frac{2}{5}x=34 \\ x=34 \times \frac{5}{2} \\ x=17 \times 5 \\ x=85$

40% of 85 is 34.

Answer 2

p%=$\frac{p}{100}$ ⇒ $\frac{40}{100}= \frac{40\div20}{100\div20}= \frac{2}{5}$

$\hbox { So, } \frac{2}{5}\cdot x=34$ ⇒ $\frac{2x}{5}=34$ ⇒ $2x=34\cdot5$

$2x=170$ ⇒ $\boxed { x=85 }$