Total ratio = 4 + 2 + 1 = 7
Unit of one ratio = 35/7 = 5
So, Number of Hours for commercial work = 5(1) = 5
Total receipt = 20 5 + 15 10 + 1 40 = 100 + 150 + 40 = 290
Commercial work receipt = 1 40 = 40
So, % = 40/290 * 100
= 400/29
= 13.79%
In short, Your Answer would be: 13.79%
Hope this helps!