Question

1. 20 in. 4 in. sa = 880

Explanation:

Step1: Identify the shape

The shape is a rectangular - prism.

Step2: Recall surface - area formula

The surface - area formula for a rectangular prism is $SA = 2(lw+lh + wh)$, where $l$ is length, $w$ is width and $h$ is height. Here, assume $l = 20$ in, $w = 4$ in, $h = 15$ in.

Step3: Calculate $lw$

$lw=20\times4 = 80$

Step4: Calculate $lh$

$lh=20\times15 = 300$

Step5: Calculate $wh$

$wh=4\times15 = 60$

Step6: Substitute into formula

$SA = 2(80 + 300+60)$
$SA=2\times440$
$SA = 880$ in²

Answer:

$880$ in²