Answer:
15 dollars spend on food .
Explanation:
As given
You leave your house with 30 dollars.
You spend an unknown amount of money on food and then spend 10 dollars on a movie .
Let us assume that the unknow amount of money spend on the food be x.
As given
If you count that you have 5 dollars left .
Than the equation becomes
30 - 10 - x = 5
20 - x = 5
20 - 5 = x
x = 15 dollars
Therefore the 15 dollars spend on food .