Hello there!
The first thing we need to do here is see which information is relevant.
The question is asking for the ratio of books to pencils.
Therefore, we only need the number of books and pencils - all other information given is irrelevant in this scenario.
Number of books - 4
Number of pencils - 7
Now, we can order this as a ratio.
A ratio is two numbers put as a proportion. It's normally written out as first number : second number.
In this case, it's the ratio of number of books : number of pencils.
Fill in the number of books and number of pencils into each side of the equation.
number of books : number of pencils
4 books : 7 pencils (the unit is normally dropped)
So therefore, 4:7 would be your final answer.
Hope this helped!