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.

Joan has 47 green and 48 red marbles . Fred took 24 of Joan 's green marbles . How many green marbles does Joan now have ?
23

A pet store had 36 siamese cats and 18 house cats . During a sale they sold 26 cats . How many cats do they have left ?
28

At the town carnival Billy rode the ferris wheel 7 times and the bumper cars 3 times . If each ride cost 5 tickets , how many tickets did he use ?

50