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]: Fred has 40 baseball cards . Keith bought 22 of Fred 's baseball cards . How many baseball cards does Fred have now ?
[EX A]: 18

[EX Q]: 29 birds were sitting in a tree . Some more fly up to the tree . Then there were 42 birds in the tree . How many more flew up to the tree ?
[EX A]: 13

[EX Q]: Joan grew 24 pumpkins , Keith grew 42 pumpkins , and Alyssa grew 13 pumpkins . They worked for 34 days on the farm . How many pumpkins did they grow in all ?
[EX A]:
79