You are given a math word problem and you are supposed to apply multiple mathematical operators like addition, subtraction, multiplication or division on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

At the fair there were 12 people in line for the bumper cars . If 10 of them got tired of waiting and left and 15 more got in line , how many people would be in line ?
17

At a sale , the cost of a pair of shoes was reduced from 42 dollars to 33.6 dollars . What was the percent of discount ?
20

Ellen made smoothies in the blender . She used 0.2 cup of strawberries , 0.1 cup of yogurt , and 0.2 cup of orange juice . How many cups of ingredients did Ellen use for the smoothies ?
0.5