40% of what number is 34?
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.
p%=\(\frac{p}{100}\) ⇒ \(\frac{40}{100}= \frac{40\div20}{100\div20}= \frac{2}{5}\)\(\hbox { So, } \frac{2}{5}\cdot x=34\) ⇒ \(\frac{2x}{5}=34\) ⇒ \(2x=34\cdot5\)\(2x=170\) ⇒ \(\boxed { x=85 }\)
