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]: A florist had 37 roses . If she sold 16 of them and then later picked 19 more , how many roses would she have ?
[EX A]: 40

[EX Q]: At the beach , Miki and her sister both built sandcastles and then measured their heights . Miki 's sandcastle was 0.8333333333333334 foot tall and her sister 's was 0.5 foot tall . How much taller was Miki 's sandcastle than her sister 's ?
[EX A]: 0.3333333333333333

[EX Q]: Fred has 5 yellow balloons , Sam has 6 yellow balloons , and Mary has 7 yellow balloons . The balloons cost 5 dollars . How many yellow balloons do they have in total ?
[EX A]:
18