A class of 32 students are supposed to take a standardized test. Out of the class, 75% of the students have already taken the test. How many students have already taken the test?         29         24         25         21

Pet Owners According to the Humane Society, in 2015, 65% of U.S. households owned at least one pet, and 42% of households who did own pets owned at least two. The U.S. Census Bureau tells us that there were 117 million households in 2015. How many households owned at least two pets? Report your answer in millions rounded to two places.

Explain why “the sum of xand y” is the same as “the sum of yand x,” but “the difference of xand y” is not the same as “the difference of yand x.” Try substituting two random numbers for x and yto help you explain.