Question

On the first day of the month, Sandra starts to read a 420-page book. She is determined to read 30

pages each night. The function P (d) = 420-30d specifies the number of pages P remaining
after Sandra does her reading on day d of the month.
Which equation offers a solution giving the day of the month Sandra finishes, and what day of the
month is that?
OP(d)=0; day 21
OP(d)-30; day 21
OP(d) = 420; day 21
OP(d) = 420; day 14
OP(d) = 0; day 14
OP (d)-30; day 14

Answer 1

P(d) = 0; 14 days

Explanation:

First part of answer: Setting P(d) = 0 would allow us to find the day Sandra finishes since P represents the pages remaining the book will be finished when there are 0 pages left to read.

Second part of answer: We can solve the equation P(d) = 0 = 420 - 30d to see how it would take 14 days to finish the book and have 0 pages left to read:

Step 1: Subtract 420 from both sides:

(0 = 420 - 30d) - 420

-420 = -30d

Step 2: Divide both sides by -3 to solve for d:

(-420 = -30d) / -30

14 = d