The important piece of information here is that 13 gallons of water makes the container 1/5 of the way full, aka 20%. If the question is simply, how many gallons will it hold, then we multiply 13 by 5 to get 100% at 65 gallons. To get the amount held at 7/10, or 70%, we simply multiply 65 with 7/10 to get 45.5 gallons.
63 degrees, if that angle is 72 that means the other must be 54 (add to 180), and if that angle on the other triangle is 54, the others must be 63 (add to 180).
