You are given a math word problem and you are supposed to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

[EX Q]: Dave had to wash 9 short sleeve shirts and 27 long sleeve shirts before school . If he had only washed 20 of them by the time school started , how many did he not wash ?
[EX A]: 16

[EX Q]: Dan has 32 green and 38 violet marbles . Mike took 23 of Dan 's green marbles . How many green marbles does Dan now have ?
[EX A]: 9

[EX Q]: A waiter had 9 tables he was waiting on , with 7 women and 3 men at each table . How many customers total did the waiter have ?
[EX A]:
90