In a primary school, the parents were asked about the number of hours they spent per day in helping their. Children to do home work. There were 90 parents who helped for `(1)/(2)` hour to `1(1)/(2)` hours. The distribution of parents according to the time for which, they said they helped is given in the figure below : `20%` helped for more than `1 ""1//2` hours per day, `30%` helped for `(1)/(2)" hour to "1 (1)/(2)` hours, `50%` did not help at all.

Using this, answer the following:
How many said that they helped for more than `1 (1)/(2)` hours?

Answer

150