75 children went to an amusement park, where they can ride on the merry go round, roller coaster, and the Ferris wheel. It is known that 20 of them taken all the three rides, and 55 of them taken have taken at least 2. Each ride costs 5 rupees and the total collection of the park was 700 rupees.
Determine the number who did not try any of the rides.
Solve by sets