Given a math word problem, answer the following question. You might need to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the question and then only report the final numerical answer.

[Q]: randy has 78 blocks . he uses 19 blocks to build a tower . how many blocks are left ?
[A]: 59

[Q]: a number machine changes the value of the numbers placed inside it . my number machine will add 15 to a number and then subtract 6 from the sum . if i put in the number 68 what number will come out of the machine ?
[A]: 77

[Q]: to make sure that the cake is sweet he needs 450 lbs . of sugar . if he has 287 lbs . of sugar stored in his house how much additional sugar will he need ?
[A]:
163