To represent the total amount of money Justin spent at the candy store, we need to sum the cost of each type of candy he bought.

1. Chocolate: Each piece costs $0.15, and he bought $c$ pieces. The total cost of the chocolate is: $0.15c$

2. Lollipops: Each lollipop costs $0.25, and he bought 3 lollipops. The total cost of the lollipops is: $0.25 \times 3 = 0.75$

3. Bubble Gum: Each piece costs $0.50, and he bought $g$ pieces. The total cost of the bubble gum is: $0.50g$

Now, sum up all these amounts to get the total cost:

$0.15c + 0.75 + 0.50g$

This expression represents the total amount of money Justin spent at the candy store.

Would you like any details or further clarification on this?

---

Here are 5 related questions for practice:

1. If Justin bought 10 pieces of chocolate and 4 pieces of bubble gum, how much did he spend in total?
2. What if lollipops cost $0.30 each instead of $0.25? How would the expression change?
3. If Justin had spent a total of $5, how many pieces of chocolate and bubble gum could he have bought?
4. How would the expression change if Justin bought 5 lollipops instead of 3?
5. If Justin bought 8 pieces of chocolate, 2 lollipops, and 6 pieces of bubble gum, how much did he spend?

Tip: When forming expressions, make sure to identify the cost per item and multiply it by the number of items purchased.