Quadrants · Medium problem

A hiking trail runs along the horizontal line $y=1.5$. It passes through the trailhead at $(-4.2, 1.5)$, a lookout at $(1.3, 1.5)$, and ends at the summit at $(7.6, 1.5)$. What is the total length of the trail from the trailhead to the summit, in units? Give your answer as a decimal.