Let's solve the following problem:
Two movie tickets and a box of popcorn cost $10. Lucy bought four boxes of popcorn and paid $8. How many dollars will he pay for a movie ticket?
Step 1
We write down the information that is given in the condition of the task:
Ticket + Ticket + Popcorn = $10
Popcorn + Popcorn + Popcorn + Popcorn = $8
Step 2
We start with the solution:
Four boxes of popcorn cost $8, so one box of popcorn costs $2.
Now we're back to a math problem - Two movie tickets and a box of popcorn cost $10, therefore two popcorn tickets cost the total ($10) from which we subtract the cost of the popcorn ($2). Thus we find that two tickets cost $8 and one ticket costs $4.
Answer: A movie ticket costs $4
* Mathematical problems with finding an unknown number can be found in the course Competitive Mathematics - Level 3