When Charlotte left her house this morning, her cell phone was 30% charged and it then started to lose 2.5% charge for each hour thereafter. Write an equation for B, in

terms of t, representing the charge remaining in Charlotte's battery, as a percentage,

t hours after Charlotte left her house.

Step-by-step explanation:

Let the initial percentage to be 30%

If it started to loose 2.5% every hour where;

t represents the time after Charlotte left her house

The amount of percent remaining every hour will form an arithmetic sequence as shown;

30, (30-2.5), (30-5.0),...

30, 27.5, 25.0...

Using the nth term for calculating an arithmetic sequence

B = a + (t-1)d

a is the first term = 30

d is the common difference = 27.5-30 = 25-27.5 = -2.5

t is the time

Substitute the given values into the formula;

B = 30 + (t-1)(-2.5)

B = 30+(-2.5t+2.5)

B = 30-2.5t+2.5

B = 32.5 - 2.5t

Hence equation for B, in  terms of t, representing the charge remaining in Charlotte's battery, as a percentage,  t hours after Charlotte left her house is B = 32.5 - 2.5t