capegemini - a college student spends 25 of his time for maths 310 of his time for science and 18 of his study time for arts if he spends remaining 30 minutes for playing with friends then find the total time taken by him to learn science and arts - skillgun

Part of the time left (remaining time) = 1 - (2/5 + 3/10 + 1/8)
1 - 33/40 = 7/40 Assume that the total time taken by him to study all subjects be x hours. We have just found that he had 7/40 remaining time after studying maths, science and arts.
From the question, we can say that he spends this remaining 7/40 of his time for playing and this time equals 30 minutes.
Then 7/40 of x = 1/2 hour
7x / 40 = 1/2
x = 20/7 hours.
Time taken to learn science = 3/10 of x = 3/10 x 20/7 = 6/7 hours
Time taken to learn arts = 1/8 of X = 1/8 x 20/7 = 5/14 hours.
Time required to learn science and arts = (1) + (2) = 6/7 + 5/14 = 17/14 hours = 1 3/14 hours.