Part A This year, water usage has increased by 20% for both regular days and special events. LAST YEAR'S WATER USAGE: All regular days - 13,505 gallons Per special event - 18.5 gallons Total for the year - 13,616 gallons "Vrite an equation for the total water usage, U, at the park this year in terms of x, the umber of special events the park has hosted. ​