The Reverse of multiplication is?

And employee salary increased by $4500 which represents a 15% raise what is the rate of the increase

Compare the subtraction problems 6/8 - 5/8 = 1/8 and 6/9 - 7/9 = 1/9 why is the answer to the first problem positive and the answer to the second problem negative

The difference of three and the reciprocal of a number is equal to the quotient of 20 and the number. find the number.