Answer:
5 tokens
Explanation:
She spent 1 out of every 4 tokens, meaning there are a couple of sets of 4 that we don't know many they are yet that she kept taking from every set 1 token, so if we do,
(Her total tokens) 20 ÷ 4 = 5.
This means that there's 5 sets, then we take 1 from every set so 1 × 5 = 5, that's it
I don't know if that was quite clear tho you can imagine it in a more virtual than mathematical way if you like,
Now Imagine you have 20 tokens in your hand, and you divide them into 5 sets, each set is a set of 4, you keep 3 in your hand then put 1 on a table, then you do this 5 times you'll end up with 5 tokens on the table and 15 in your hand.
You can try that yourself if you want it to be more clear.
Take 20 small pieces of paper, sticky notes or coins whatever you like, then divide them into sets of 4, then lastly take only 1 from each set (and by the way you'll notice that dividing each set into a set of 4 will make you automatically end up with 5 sets) now count all the 1's you collected from each set
they should be 5.