Question

△abc ~ △def
find the value of x.

Explanation:

Step1: Set up proportion

Since $\triangle ABC\sim\triangle DEF$, the ratios of corresponding sides are equal. So, $\frac{AC}{DF}=\frac{BC}{EF}$, which gives $\frac{x}{9}=\frac{15}{5}$.

Step2: Solve for x

Cross - multiply: $5x = 15\times9$. Then $5x=135$. Divide both sides by 5: $x=\frac{135}{5}=27$.

Answer:

$27$