Question

A girl is the same age if she takes 3/4 of her age +9 or 1/4 +21. what is her age?

Answer 1

let's say she's "x" years old.


`\bf \stackrel{her~age}{\cfrac{3x}{4}+9}~~=~~\stackrel{her~age}{\cfrac{x}{4}+21}\impliedby \textit{now, let's multiply both sides by }\stackrel{LCD}{4} \\\\\\ \boxed{4}\cdot \cfrac{3x}{4}+\boxed{4}\cdot 9~~=~~\boxed{4}\cdot \cfrac{x}{4}+\boxed{4}\cdot 21\implies 3x+36=x+84 \\\\\\ 2x=48\implies x=\cfrac{48}{2}\implies x=24`