We know the total amount of money Drew earned from selling = $64. Since he is only selling two items, lemonade and apples, we can turn the info into an equation: lemonade + apples = $64 (or L + A = 64)
We also know that he sold $21 in lemonade. If we plug that into our new equation, it looks like this:
21 + A = 64
From there we just need to find A (the amount of money he earned from selling apples). We can do this by subtracting 21 from 64:
