I am not sure what the six-step method looks looks like but if you use x gallons of 60% solution the amount of antifreeze in the mixture = 0.6x + 8 gallons This needs to be 50% of the total quantity in the mixture, x + 80 0.6x + 8 = 0.5(x + 80) 0.6x + 8 = 0.5x + 40 0.6 - 0.5 = 40 - 8 0.1x = 32 x = 32 x 10 = 320 gallons
