I know the answer, but I need to know why its right..

Angela & Neil are going to the movies. They each bought a medium popcorn, and Neil got a small soft drink. Angela had a $5 gift certificate to put toward the cost, which came to $27.90. A movie ticket cost $10 each, and a medium popcorn costs $5.50. What was the cost for the soft drink?

Question

I know the answer, but I need to know why its right..

Angela & Neil are going to the movies. They each bought a medium popcorn, and Neil got a small soft drink. Angela had a $5 gift certificate to put toward the cost, which came to $27.90. A movie ticket cost $10 each, and a medium popcorn costs $5.50. What was the cost for the soft drink?

anonymous · Answer

The answer is $1.90 , but why ?!

anonymous · Answer

So, 2 people going

movie ticket is $10 each
so 2 x 10 = 20

add on the popcorn
20 + 5.50x 2 = 20 + 11 = 31
(times 2 because there is 2 popcorns one for each)

angela has a  5 gift certificate, so take away 5
so we get 31 - 5 = 26

Now the total cost was 27.90, so the difference is the price of the drink which is
27.90 - 26 = 1.90

which is reasonable for a small drink in a cinema