Chapter 3 Linear Systems and Matrices - 3.1 Solve Linear Systems by Graphing - 3.1 Exercises - Problem Solving - Page 158: 40b

$15\text{ ft/s}$

Let $s$ be the speed at which your friend travels. The time he travels equals the time you travel, which is: $$t=\dfrac{2000+3000}{25}=\dfrac{5000}{25}=200\text{ s}.$$ We calculate your friend's speed: $$s=\dfrac{3000}{t}=\dfrac{3000}{200}=15\text{ ft/s}.$$