Solve the Problem $2.5 \mathrm{~km} / \mathrm{hr}$ They Meet in 4 Hours

Solve the problem.
-Jill is 22 kilometers away from Joe. Both begin to walk toward each other at the same time. Jill walks at $2.5 \mathrm{~km} / \mathrm{hr}$ . They meet in 4 hours. How fast is Joe walking?

A) $3 \mathrm{~km} / \mathrm{hr}$
B) $8 \mathrm{~km} / \mathrm{hr}$
C) $12 \mathrm{~km} / \mathrm{hr}$
D) $2.75 \mathrm{~km} / \mathrm{hr}$