The problem asks to find the straight-line distance from the starting point after driving 18 miles east and then 5 miles south. We need to round the answer to the nearest tenth of a mile.

1. Problem Description

The problem asks to find the straight-line distance from the starting point after driving 18 miles east and then 5 miles south. We need to round the answer to the nearest tenth of a mile.

2. Solution Steps

The eastward and southward movements are perpendicular to each other. Therefore, the straight-line distance from the starting point can be calculated using the Pythagorean theorem. Let $a$ be the distance traveled east (18 miles), $b$ be the distance traveled south (5 miles), and $c$ be the straight-line distance from the starting point.

We have:

$c^2 = a^2 + b^2$

$c = \sqrt{a^2 + b^2}$

Substitute the given values:

$c = \sqrt{18^2 + 5^2}$

$c = \sqrt{324 + 25}$

$c = \sqrt{349}$

$c \approx 18.6815$

Round to the nearest tenth:

$c \approx 18.7$

3. Final Answer

18.7