Question

Jeff starts driving at 45 miles per hour from the same point that Lauren starts driving at 40 miles per hour. They drive in opposite directions, and Lauren has a half-hour head start. How long will they be able to talk on their cell phones that have a 270-mile range?

Answer 1

45x +40(x+0.5) =270

45x +40x +20 =270

85x = 250

x = 250/85 = 2.94 

45 * 2.94 = 132.3 miles

40*(2.94 +0.5) = 40*3.44 = 137.6

2.94 hours