Question 1052216
distance = rate*time, for short: d = rt
Let r be Chuck's speed. Then, Dana's speed will be r-3
apply the formula to:
Chuck: 93 = rt
Dana: 84 = (r-3)t
Put it all together:
93/r = 84/(r-3)
Cross multiply:
93(r-3) = 84(r)
93r-93*3 = 84r
93r-84r = 93*3
9r = 279
r = 279/9
r = 31
Your answer:
Chuck: 93/31 = 3 so Chuck drives for 3 hours at 31mph
Dana: 31-3 = 28 so she drives for 3 hours at 28mph

Answer:
Chuck is driving at 42 mph (for 2 hours)
Dana is driving at 39 mph (for 2 hours)