Rocco and Guilia can paint and finish together in 3 hours while Rocco alone can do it alone in 7 hours. Guilia at the rate of 1/r can finish the job expressed in the following equation. 1/3= 1/7+1/r. Getting r, r is equal to 5.25 hrs. Hence, Guilia can do painitng alone in 5.25 hrs.
