To find the expression for the number of apples Frankie had, we know that Frankie has 7 more apples than Mollie. So, if Mollie has "d" apples, then Frankie would have "d + 7" apples.
Let's break it down step by step:
1. Start with the number of apples Mollie has, which is represented by "d".
2. Add 7 to that, since Frankie has 7 more apples.
3. Combining these two steps, we can express the number of apples Frankie had as "d + 7".
For example, if Mollie had 10 apples, then Frankie would have 10 + 7 = 17 apples.