Answer: 21 calories
Explanation:
Lets say the glasses of milk is defined by the variable "g". And the snack bars are defined by the variable "s".
Your equation, based off of the information given should be this:
4g + 3s = 74
2g + 4s = 62
Now you have a set of equations. Now combine.
4g + 3s = 74
-2(2g + 4s) = 62(-2)
4g + 3s = 74
-4g - 8s = -124
-5s = -50
-5s/-5 = -50/-5
s = 10
So now that you know how much one snack bar contains (10 cal) then substitute this info in one of the equations:
2g + 4(10) = 62
2g + 40 = 62
2g = 22
g = 11
Therefore one glass of milk has 11 cal and one snack bar has 10 cal. in total, 21 calories.