Grandma baked many biscuit cakes. She glazed a quarter of all the cakes with chocolate, and decorated a third of the rest of the
cakes with nuts. Half of the remaining cakes were decorated with fruit, and then she put whipped cream on the final 15 cakes. How many cakes did Grandma bake?
so the first thing is 1/4 of the whole thing is gone. Then a third of the now 3/4 is another 1/4 which makes 1/2. A 1/2 of 1/2 is a 1/4 which means the last 1/4 is 15. Then do 15*4 to get your answer.