In this equation, let "x" equal the rate at which the tub will be filled. The tub holds 32 gallons, which will be one half of the equation. The tub already contains 12 gallons, so this will be half of the other side of the equation. The rate is "x" gallons per minute, and the time it required was 5 minutes, so this would be "5x". Placing all these parts together gives an equation of (32 = 5x + 12) gallons per minute dispensed.
