Anyone please answer this question?

Subtracting is the opposite of adding

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.

The first digit is in the middle school 100s place

1+1=22×1=22-1=11-1=1duh