Correct. 2 hours for 20 steering wheels is the same rate as 10 steering wheels per hour, so together they can install 10+15=25 each hour. To find how long it would take to install 200, set up and solve the equation $\displaystyle\frac{{25}}{{1}}=\frac{{200}}{{h}}\usepackage{cmbright}\Huge\$ , where h=hours. You find h=8.