What's the Error?

Judy added 2 quarts of water to 2 pints
of juice concentrate. She says she ended up with 1 gallon of juice. Describe and correct her error.

A pint is half a quart.

so she really added 2 quarts of water and 1 quart of concentrate
and ended up with 3 quarts of juice
3 quarts is 3/4 of a gallon, not a gallon