18 x 3 = 54. So the correct answer is D. 54 pounds.
Divide 309 by 3. You should get 103 (hamburgers). if you multiply that by 2 you will get 206 (cheeseburgers). Add the two together you get the total which was 309 originally.
103 hamburgers and 206 cheeseburgers.
Looking at the given points on the right side from (0,2) to (1,6) for 1 increase in X ( 1-0=1) the Y value increases by 3 ( 6/2 = 3)
This same increase happens for th other two points: 18/6 = 3
54 / 18 = 3
The rate of increase is 3.