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.

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?
53

Context: Marco and his dad went strawberry picking. Marco's strawberries weighed 30 pounds. If together their strawberries weighed 47 pounds. 

 Question: How much more did his strawberries weigh than his dad's?
13

Context: In a school there are 697 girls and the rest are boys. If there are 228 more girls than boys 

 Question: How many boys are there in that school?

469