Why do we add the opposite when subtracting integers ?

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?

Afarm that has 4 x 10^2 acres has 1.2 x 10^5 cattle. what is the average number of cattle per acre? write the answer in scientific notation. answere asap

If (17, 4) is an ordered pair of the inverse of f(x), which of the following is an ordered pair of the function f(x)? a. (17,4) b. (4.17) c. (4,0) d. 0,17)