Alex has a 10-gallon keg of wine and a big ladle. On Monday, Alex drew off a ladle-full of wine and filled the keg back up with water. On Tuesday, he repeated the process, making sure to mix the contents in the keg around first. On Wednesday morning, he realized that the keg now contains equal parts of wine and water. How many gallons can the ladle hold? The answer is in the form with . Find .