The equation p=100-10t represents the percent p of battery power remaining in a cell phone after t hours

We have the equation:

P(t) = 100 - 10*t

where t is the number of hours.

at t = 0, we have:

P(0) = 100 - 0 = 100

so at the initial time, we have 100% of the battery power.

Now with this equation we can find the numbers of hours that we have left in our phone, this is finding the time t at which the power left is equal to zero:

P(t) = 0 = 100 - 10*t

10*t = 100

t = 100/10 = 10

So the battery power will last for 10 hours.

(8 x 9) x (2 x 5) is the correct answer.

Step-by-step explanation:

(8 x 9)= 72

(2 x 5)= 10

72 x 10 = 720