Gravity Adjustment

I made a pale ale yesterday. I finished my boil with 4.5 gallons of 1.060 wort. I then added one gallon to top up to 5.5 gallons. Can anyone give me the formula to adjust my gravity?

Thanks!

60 points in 4.5 gallons is (60 * 4.5) 270 “gravity points” total.  When you add a gallon of water to get to 5.5 gallons, you’re not adding any points so you still have 270 gravity points but now it’s in 5.5 gallons.  So, you’re new gravity is (270 / 5.5 = 49) 1.049.