salt water is flowing into an aquarium that contains pure water. The concentration of salt in the aquarium, (c), in grams per 1 liter (g/l) at time (t) in minutes is given by the formula C = 6t/40+t. When does the concentration in the aquarium reach 3.5g/l

If she ran a 440 yd track 20 times, you would multiply the two numbers together. Each lap around the track would be 440 yds, so if she ran 440 yards 20 times (440 * 20), she would have ran 8,800 yards. Convert this to feet to find the distance in miles (one yard is 3 feet, so she ran 8,800*3 = 26,400ft). One mile is 5280 feet, so divide the feet she ran by the number of feet in a mile. The answer is 5. She ran 5 miles.