Question 911750: In Linear Equation Homework:
"Matt loves biking. He bikes uphill at 4 mph, downhill at 6 mph, and manages to cover 18 miles in 4 hours. How many miles did he bike downhill?"
I normally have problems with speed, distance and time. I thought maybe 18/4= something. I don't know what to do with the 4 mph and 6 mph. I know I ought to add them or something similar, but I can't decide about the mph part. Does the unit cause the question to differ? I simply can't put one end with the other.
Thanks.
Found 3 solutions by josgarithmetic, MathTherapy, richwmiller:
Answer by josgarithmetic(39626)   (Show Source):
You can put this solution on YOUR website! Being a travel problem with simple rates and distance,
RT=D uniform rates rule for travel, RATE, TIME, DISTANCE.
4 mph uphill and 6 mph downhill.
18 miles in 4 hours.
Some thinking...
Nothing comes into mind easily. Try making a table of data.
______________rate___________time__________distance
UPHILL________4_______________x
DOWNHILL______6_______________y
Notice the assigning of variables for times.
Use RT=D idea to put in expressions for distances.
______________rate___________time__________distance
UPHILL________4_______________x____________4x
DOWNHILL______6_______________y____________6y
You were given the total time and total distance.
______________rate___________time__________distance
UPHILL________4_______________x____________4x
DOWNHILL______6_______________y____________6y
Totals________________________4____________18
You may be able to now see what next to do. Tell me if you still have trouble continuing from this data table.
Answer by MathTherapy(10556)  (Show Source):
You can put this solution on YOUR website!
In Linear Equation Homework:
"Matt loves biking. He bikes uphill at 4 mph, downhill at 6 mph, and manages to cover 18 miles in 4 hours. How many miles did he bike downhill?"
I normally have problems with speed, distance and time. I thought maybe 18/4= something. I don't know what to do with the 4 mph and 6 mph. I know I ought to add them or something similar, but I can't decide about the mph part. Does the unit cause the question to differ? I simply can't put one end with the other.
Thanks.
Let distance he biked downhill be D
Then distance biked uphill = 18 D
We then get: D/6 + (18 - D)/4 = 4
2D + 3(18 D) = 48 ------- Multiplying by LCD, 12
2D + 54 3D = 48
2D 3D = 48 54
- D = - 6
D, or distance biked, downhill =  , or  miles
You can do the check!!
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Answer by richwmiller(17219)  (Show Source):
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