What is the side length of the largest square tile that can be used to tile a rectangular floor measuring 12 ft by 38 ft if the tiles cannot be cut?

The greatest common facter of 12 and 38 is 2 so the answer is:
2 ft

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.