A shop had a total of 964 strawberry and blueberry muffins. After selling 5/6 of the strawberry muffins and 2/5 of the blueberry muffins, there were 54 more blueberry muffins than strawberry muffins left. (a) How many strawberry muffins were there at first? (b) The remaining muffins were sold at 3 for $4. Colin bought all the remaining muffins. How much dod he pay for the muffins?