Final answer:
To find the number of pages left to read, we subtract the pages read (-2b+78) from the total pages in the book (10b+3), resulting in 12b-75 pages left, which corresponds to option D.
Step-by-step explanation:
The question is about finding the number of pages a student has left to read from a book. The total number of pages in the book is given as 10b+3, and the number of pages already read is -2b+78. To find the number of pages left, we need to subtract the pages read from the total number of pages:
Total pages in the book: 10b + 3
Pages read: -2b + 78
To find the number of pages left, calculate: (10b + 3) - (-2b + 78) which simplifies to:
- 10b + 3 + 2b - 78
- 12b + 3 - 78
- 12b - 75
Therefore, the number of pages left to read is 12b - 75, which matches option D from the choices provided.