When Helen jogs, every $20$ minutes she checks the total distance she traversed. One day, the first time she checked, Helen had jogged a distance of $2.5$ miles, the second time she checked, she had jogged a total distance of $4.8$ miles, and the third and final time that she checked, Helen found out that she jogged a total distance of $6.8$ miles. What is the difference between her average speeds, in miles per hour, during the first $20$ minutes of jogging and the last $20$ minutes of jogging?

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?