(13) The ratio of the number of cheese muffins to the number of chocolate muffins in a confectionery was 3:2. After 144 cheese muffins were sold, the ratio of the number of cheese muffins to the number of chocolate muffins changed to 3:5. How many more cheese muffins than chocolate muffins were there at first?

(9) The ratio of the number of men to the number of women on a bus was 2: 3. At a bus stop, 4 women got off and the ratio became 4:5.
a) How many men were on the bus?
b) How many women were on the bus in the end?