1. The girls spent $18 on tickets
2. Not enough information was provided
3. The last product would be 3x2 if Amber had bought only 3 tickets.
1) Gathering the data:
Jen: 4 tickets
Amber: 5 tickets
Price of each: $
2) To find out how much did the girls spend let's write out an expression:

So the girls spent $18 on tickets in all.
3) If Amber had bought only 3 tickets then this equation would change this way:

The factor 5 would be replaced by 3 then.
3) Hence the answer is:
1.The girls spent $18 on tickets
2. Not enough infomation provided
3. The last product would be 3x2 if Amber had bought only 3 tickets.