Given the equation G = 50 + 20T, where G = the total amount of gas and T = the amount of Time, we know that there is already 50 gallons of gas in the tank and that the rate at which it is pumped is 20 gallons per minute (I am assuming, though it is not stated in the problem). Given that the tank holds 850 gallons, we can plug in the values into the equation and solve for the missing variable, T:
850 = 50 + 2T
Subtract 50 from both sides: 850 - 50 = 50 + 2T - 50 or 800 = 2T
