Students took at least two of the three rides = d + e + f + 35 = 60
Only two rides = d + e + f = 25
Each ride costs Rs.2
Total receipt from students those who took all the three rides = 35 * 6 = Rs.210
Total receipt from students those who took only two rides = 25 * 4 = Rs.100
Total receipt from students those who took all the three rides and those who took only two rides=210 + 100 = Rs.310
Total collection = Rs.350
Balance amount Rs.40 was collected from those students those who took only one ride.
Only one ride = a + b + c = 20. Hence (c).
Number of students who took atleast one ride = 20 + 25 + 35 = 80
Then the number of students who did not took any ride = g = 110 – 80 = 30