## College Algebra 7th Edition

Let's say that the assistant worked $t$ hours. Then the plumber worked $2*t$ hours. The final bill was \$4025:$4025=25*t+45*2t$We solve for$t$:$4025=115*tt=4025/115=35\$ Thus the assistant worked 35 hours and the plumber worked 35*2=70 hours.