What number could be added to the quotient of (-72) ÷ (-8) so that the sum is equal to -24 ?

Scott harris can invest $7,000 in a 1-year cd that earns interest at an annual rate of 4 percent compounded monthly. the amount per $1.00 is 1.040742. he can also invest $7,000 in a 1-year cd at annual rate of 4 percent compounded quarterly. the amount per $1.00 is 1.040604. what is the difference in the amount of interest earned for each investment? a) $0.96 b) $0.81 c) $0.87 d) $0.88

One side of a rectangle is 7 feet shorter than seven times the other side. find the length of the shorter side if we also know that the perimeter of the rectangle is 306 feet.

How do you use the elimination method for this question? explain, because i really want to understand!