Use the given scale factor and the side lengths of the scale drawing to determine the side lengths of the real object. Scale factor: 3:1 18 in 다. 21 in Scale drawing Object A. Side ais 7 inches long and side bis 6 inches long. B. Side a is 24 inches long and side bis 21 inches long. C. Side a is 18 inches long and side bis 15 inches long. D. Side a is 63 inches long and side bis 54 inches long.​

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.