Question 842505
Rowena, 1/5 car per hour
Rudolf, 1/8 car per hour


Let t = unknown time that rowena paints the car alone


{{{highlight_green((1/5+1/8)2+(1/5)t=1)}}}, the completion of one whole job of "paint the car".  Solve for t.


Multiplying both sides by 40 clears the denominators.
{{{(8+5)2+8t=40}}}
{{{13*2+8t=40}}}
{{{8t+26=40}}}
{{{4t+13=20}}}
{{{4t=7}}}
{{{t=7/4}}}
{{{highlight(t=1&3/4)}}} hours.