Respuesta :

3/4 - 1/8 = 5/8, so 5/8 tank(42 gallons) of water is added to the tank, so 1/8 tank of water is 8.4 gallons of water, and 1/2 is 4 x 1/8 so 4x8.4= 33.6 gallons.
Answer: 33.6 gallons of water is in the tank when it is 1/2 full.