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.

[EX Q]: Context: After Olivia visited a supermarket there were 29 dollars left. If there were 54 dollars in her wallet initially 

 Question: How much did she spend?
[EX A]: 25

[EX Q]: Context: Next on his checklist is wax to stick the feathers together. He needs 159 g of wax more. If the feathers require a total of 628 g of wax 

 Question: How many grams of wax does he already have?
[EX A]: 469

[EX Q]: Context: Paul had 50 books. After buying some in a garage sale he had 151 left. 

 Question: How many books did he buy?
[EX A]:
101