Wally is playing with his toy robot. The robot's battery is 85% full when he starts playing with it. The battery drains to 74% after Wally plays with the robot for 40 minutes.

Question

If t represents the time elapsed in minutes and l represents the battery level, which of the following equations can be used to model this situation?
A. l = 85t + 0.275

B. l = -0.275t - 85

C. l = -0.275t + 85

D. l = -0.275t + 85t

Answer 1

B. l = -0.275t - 85

Answer 2

Barry is organizing a holiday party and researching the cost of invitations. The table shows the total cost, y, for a given number of invitations, x.

Number of Invitations, x Total Cost, y ($)
10 29
20 54
30 79
40 104

Which equation describes the relationship between the number of invitations and the total cost?
A. y = 10/3x = 4

B. y = 5/2x - 4

C. y = 2/3x + 4

D. y = 5/2x + 4

Answer 3

B. y = 5/2x - 4