The 4 zeroes in 10,000 tell me to move the decimal 4 places to the right

Which equation represents the partial sum of the geometric series?

Scale factor of 2 is used to enlarge a figure as shown below the area of is 18 in.²

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.