What is the greatest common factor of 42 and 84

a) 7
b) 21
c) 42
d) 84

The answer for this question is 80

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.