Answer:
Tony needs $20 more to buy everything.
Explanation:
1. Add the prices of what Tony wants to buy together. ($6 +$18 + $6=?)
2. Add the amount of money Tony has now together. ($6 + $4=?)
3. Subtract the second amount ($6 + $4=?) from the first amount ($6 +$18 + $6=?) and that is your answer ($20)