Question

find the surface area of the rectangular prism.

Explanation:

Step1: Recall surface area formula

The surface area $S$ of a rectangular prism is given by:
$$S = 2(lw + lh + wh)$$
where $l=7$ km, $w=3$ km, $h=5$ km.

Step2: Calculate each face area sum

First compute the products inside the parentheses:
$$lw = 7 \times 3 = 21$$
$$lh = 7 \times 5 = 35$$
$$wh = 3 \times 5 = 15$$
Sum these values:
$$21 + 35 + 15 = 71$$

Step3: Multiply by 2 for total area

Multiply the sum by 2 to account for all faces:
$$S = 2 \times 71 = 142$$

Answer:

142 square kilometers