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

[Q]: Context: Julia played tag with 5 kids on tuesday. She had played tag with 6 kids on monday. 

 Question: How many more kids did she play with on monday than on tuesday?
[A]: 1


[Q]: Context: David did 51 push-ups in gym class today. David did 49 more push-ups than Zachary. 

 Question: How many push-ups did Zachary and David do altogether?
[A]: 53


[Q]: Context: There were 13 roses in the vase. Jessica cut some more roses from her flower garden which had a total of 12 roses. There are now 21 roses in the vase. 

 Question: How many roses are left in the garden?
[A]:
4