Jose works out at a gym. He rides a stationary bike for a certain amount of minutes and walks on a treadmill for a certain amount of minutes every time he works out. The time on each machine varies, but he spends between 60 and 90 minutes at the gym every time he visits. The machines keep track of how many calories he burns per minute. He burns 9 calories per minute on the bike and 5.5 calories per minute on the treadmill. Jose burns between 500 and 700 calories per visit. When graphing these lines to find the possible number of calories burned during a particular visit to the gym, which of the following linear equations would NOT be used to find the shaded region on the graph? Let x represent the amount of time on the bike, and y represent the amount of time on the treadmill.
a) y≤700−5.5x / 9
b) y≥60−x
c) y≤90−x
d) y≥500−9x / 5.5