<h3><u><em>Answer:</em></u></h3><h3><u><em>30</em></u></h3><h3><u><em>Step-by-step explanation:</em></u></h3><h3><u><em>Answer: 30 gallons</em></u></h3><h3><u><em></em></u></h3><h3><u><em>Step-by-step explanation:</em></u></h3><h3><u><em></em></u></h3><h3><u><em>So fist we add 40% and $40%. That's 80 percent of the tank which is 12 + 12 = 24. </em></u></h3><h3><u><em>Then we figure out half of 40 percent which is 20 which means its 6 gallons. </em></u></h3><h3><u><em>Now we add. 12+12+6 which equals our answer 30 gallons</em></u></h3><h3><u><em></em></u></h3>