Solve for linear equations y=--2x+18 4y-x+9=0

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.

Given the equation    = 5, solve for x and identify if it is an extraneous solution

Which is the standard form for this number? (2 x 10) + (5 x 1) + (8 x 1 10,000 )