Question

triangle x is a scaled copy of triangle w.

Explanation:

Step1: Set up proportion

Since the two triangles are similar (scaled - copies), the ratios of corresponding sides are equal. Let the side of length 15 in triangle W correspond to the side of length y in triangle X, and the side of length 25 in triangle W correspond to the side of length 20 in triangle X. The proportion is $\frac{15}{y}=\frac{25}{20}$.

Step2: Cross - multiply

Cross - multiplying the proportion $\frac{15}{y}=\frac{25}{20}$ gives us $25y = 15\times20$.

Step3: Calculate the right - hand side

$15\times20=300$, so the equation becomes $25y = 300$.

Step4: Solve for y

Divide both sides of the equation $25y = 300$ by 25: $y=\frac{300}{25}=12$.

Answer:

12