#### Answer

The person's speed in still water is 5.5 mi/h, and the current speed is 1.5 mi/h.

#### Work Step by Step

Let x = the person's speed in still water and let y = the speed of the current
We have the system:
$x-y=4$
$x+y=7$
Use elimination to solve for x.
$2x=11$
$x=5.5$
$\rightarrow y=1.5$
The person's speed in still water is 5.5 mi/h, and the current speed is 1.5 mi/h.