Hi, the answer is "You pay $11 for a movie ticket and some amount at the concession stand for a total of $28". We know this because the key words "total" before $28 dollars - 'total' stands for an equal sign in equations.
The unknown, or x, is the "some amount at the concession stand". This is an unknown value, but we do know it is added to $11 dollars for the movie ticket (which is a known value.)
Therefore, we have 11 (the movie ticket) plus (key word: and) some amount (meaning x) = (key word: total) 28