Which equation represents a hyperbola? 4x2 + 3x + 4y2+ 5 = 0
2x2 – 5xy + 4y2 + 10x – y + 12 = 0
3x2 – 6xy + 3y2 + 5x – 2y + 1 = 0
3x2 + xy – 9y2 + 2x + 5 = 0

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 4 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 –0.414t + 129.549, where t is the number of minutes and 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?