High School

A girl read a book that had 1,159 pages. She read 72 pages on the first day and then read 40 pages per day until she finished the book.

Which equation can be used to find the number of days, [tex]\( d \)[/tex], it took her to read the book?

A. [tex]\( 72 + 40d = 1,159 \)[/tex]

B. [tex]\( 72d - 40 = 1,159 \)[/tex]

C. [tex]\( 40d + 72 = 1,159 \)[/tex]

D. [tex]\( 40d - 72 = 1,159 \)[/tex]

Answer :

Sure! Let's find the equation that can be used to determine the number of days, [tex]\(d\)[/tex], it took the girl to read the book.

1. Total Pages: The book has 1,159 pages in total.

2. First Day Reading: She read 72 pages on the first day.

3. Pages After the First Day: After reading 72 pages, the remaining pages she needs to read are:
[tex]\[
\text{Remaining Pages} = 1,159 - 72 = 1,087
\][/tex]

4. Daily Reading After First Day: She reads 40 pages per day after the first day.

5. Determine the Equation: We need to find how many days, [tex]\(d\)[/tex], it takes to read the 1,087 remaining pages at 40 pages per day. The equation for the remaining pages would be:
[tex]\[
40d + 72 = 1,159
\][/tex]

Here’s why this equation works:
- [tex]\(40d\)[/tex]: Represents the pages read after the first day.
- [tex]\(+ 72\)[/tex]: Adds the pages read on the first day.
- [tex]\(= 1,159\)[/tex]: Total number of pages in the book.

So, the correct equation to find the number of days it took her to read the book is:
[tex]\[ \boxed{40d + 72 = 1,159} \][/tex]

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