Answer: The correct option is
(A) at the most 10.
Step-by-step explanation: Given that Mary’s parents gave her $60 as pocket money to meet her daily expenses. She spent $20 on clothes and $10 on food.
Also, she wishes to buy some books and each book costs $3.
We are to solve the inequality to find the number of number of books that she can buy.
Let the number of books that Mary can buy be n.
Then, according to the given information, we have
![20+10+n*3\leq 60\\\\\Rightarrow 30+3n\leq 60\\\\\Rightarrow 3n\leq 60-30\\\\\Rightarrow 3n\leq 30\\\\\Rightarrow n\leq (30)/(3)\\\\\Rightarrow n\leq 10.](https://img.qammunity.org/2020/formulas/mathematics/high-school/lefmrw639a2h97ql826eta6y01oa0jdwhl.png)
Thus, Mary can buy at most 10 books.
Option (A) is CORRECT.