Titus works at a hotel. Part of his job is to keep the complimentary pitcher of water at least half full and always with ice. When he starts his shift, the water level shows 8 gallons, or 128 cups of water. As the shift progresses, he records the level of the water every 10 minutes. After 2 hours, he uses a regression calculator to compute an equation for the decrease in water. His equation is W approximately equal to negative 0 point 4 1 4 t plus 129 point 5 4 9 , where t is the number of minutes and cap w is the level of water. According to the equation, after about how many minutes would the water level be less than or equal to 64 cups?