Question

Bob's gas tank is 1/2 full. After he buys 3 gallons of gas, it is 2/3 full. How many gallons can Bob's tank hold?

Answer 1

(2/3)*x - (1/2)*x = 3
*make common denominators
(2*2)/(2*3)*x - (3*1)/(3*2)*x = 3
(4/6)*x - (3/6)*x = 3
(1/6)*x = 3
x = 3*(6/1)
x = 3*6
x = 18 gallons of gas