Hey there!
Since there will likely only be one lunch and one set of gym clothes, we can simply add those two weights together and subtract them from the total amount of weight Toni can carry.
18 – (1 + 2) = 18 – 3 = 15
Now, just divide the remaining amount of weight available by three. The answer will be how many books she can carry.
15 ÷ 3 = 5
Toni can carry her lunch, her clothes, and 5 books in her backpack.
Hope this helped you out! :-)
