Can someone help me please

This is the number of parts out of 100, the numerator of a fraction where the denominator is 100. submit

Which representation has a constant of variation of -2.5

Three numbers x, y, and z are in the ratio 2: 7: 8. if 12 is subtracted from y, then three numbers form a geometric sequence (in the order x, y–12, z). find x, y, and z. there are 2 sets.