When the following expression is written in simplest form, what is the coefficient of the variable term? -2.5y + 8y - 10.5y

-5
5.5
0
-21

Which ordered pair (c,d) is a solution to the given system of linear equations- c+2d=13 -9c-4d=-15

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

Twenty points. suppose that one doll house uses the 1 inch scale, meaning that 1 inch on the doll house corresponds to 1/2 foot for life-sized objects. if the doll house is 108 inches wide, what is the width of the full-sized house that it's modeled after? in inches and feet