SOLUTION: I'm having a problem with this world problem finding an equation for it. I was able to make a chart and figure it out but I'm supposed to find an equation for it and I'm not sure h

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Question 331889: I'm having a problem with this world problem finding an equation for it. I was able to make a chart and figure it out but I'm supposed to find an equation for it and I'm not sure how to do it. The question is this:
Agnes and Jamie left the apartment at the same time traveling in the same direction (along the same road). Agnes is traveling at 54 mph and Jamie at 60 mph. How many hours will it be before Jamie is 12 miles ahead of Agnes?
54 1 hr 60
108 2 hr 120 120-108=12 (that's how I figured the answer out but I have to have an equation.)
I have charted and understand that it will be 2 hours before Jamie is 12 miles ahead of Agnes and I know that distance = speed x time. But, I only have one of those variables. I just have their speed. The distance totally traveled is not what I'm looking for and the 12 miles they speak about is not the total distance so that equation doesn't fit. Is there a different equation I should be aware of? I've looked through my book and am not finding it anywhere. Any help would be appreciated.
Found 2 solutions by nerdybill, Alan3354:
Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website!

Agnes and Jamie left the apartment at the same time traveling in the same direction (along the same road). Agnes is traveling at 54 mph and Jamie at 60 mph. How many hours will it be before Jamie is 12 miles ahead of Agnes?
.
Applying the distance formula:
d = rt
.
Let t = time when Jamie is 12 miles ahead of Agnes
then
"distance traveled by Agnes" + 12 = "distance traveled by Jamie"
54t + 12 = 60t
12 = 6t
2 hours = t

Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website!
Jamie is moving away from Agnes at 6 mph (60 - 54)
12 miles/6 mph = 2 hours