There were twice as many chocolate tarts as apple tarts in a shop at first. 3/4 of the chocolate tarts and 2/3 of the apple tarts were sold in the morning.
(a) What fraction of the total number of tarts were left unsold in the morning?
(b) 5/6 of the remaining chocolate tarts were sold in the afternoon. Then, there were 60 more apple tarts than chocolate tarts in the end. How many chocolate tarts were there at first?
