Question

Wally is playing with his toy robot. The robot's battery is 80% full when he starts playing with it. The battery drains to 74% after Wally plays with the robot for 40 minutes. 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 = -0.15 + 80t
B. l = -0.15t + 80
C. l = 80t + 0.15
D. l = -0.15t - 80

Answer 1

The answer is D .
For your question

Answer 2

Answer:

B. l = -0.15t + 80

Step-by-step explanation:

From the options we can see that the relation between the battery level (I) and the time elapsed (t) is modeled by the equation of a line, that is:

I = a*t + b

where a and b are some constants, I is in % and t is in minutes.

At t = 0 (when Wally starts to play) the battery is 80%, that is:

80 = a*0 + b

80 = b

At t = 40 minutes the battery is 74%, then:

74 = a*40 + 80

74 - 80 = a*40

-6 = a*40

-6/40 = a

-0.15 = a

Then, the equation is I = -0.15*t + 80