So, personally I would take 252 and divide it by 4. this will give you 63 which is 1/4 of the cookies. Then add that 63 three times to get a total of 189 cookies which would be your 3/4 sold. so since there is only 63 cookies left then you would go into your final problem. 3/9 is equal to 1/3, so all you would do is divide 63 by 3 and get a total of 21 cookies given to the pta.
