How much milk does the plastic jug contain?

Question

A plastic jug contains 2g gallons of milk more than a carton of milk. The plastic jug and the carton contain (8g+6) gallons of milk altogether.

Answer 1

Let X be the amount of milk in the carton.  

Then X + 2g is the amount in the jug.  

Total amount is X + X + 2g = 8g + 6

2X = 6g + 6

X = 3g + 3 is the amount the carton contains.  

So 5g + 3 is the amount the jug contains.