Question

c. 3
perimeter = 60
hint (c)::

Explanation:

Step1: Find the width of the larger rectangle

Use the perimeter formula \(P = 2(l + w)\). Given \(P = 60\) and \(l=21\).

$$60=2(21 + w)$$

$$30=21 + w$$

$$w = 9$$

Step2: Set up the proportion

Since the rectangles are similar, \(\frac{3}{9}=\frac{x}{21}\)

Step3: Solve for \(x\)

Cross - multiply: \(9x=3\times21\)

$$9x = 63$$

$$x=\frac{63}{9}=7$$

Answer:

\(x = 7\)