Multifunction: 2 people drove 490 miles in 11.4 hours.

[RyderB]

I need help with this. 2 people drove 490 miles in 11.4 hours. Driver A drove the first part of the trip and averaged 35 mph and Driver B drove the remainder and averaged 45 mph. For what length of time did Driver A drive?

[stapel_eliz]

Pick a variable to stand for the time that the first driver spent driving. Use the formula "d = rt": multiply the rate by the time to get an expression for the first driver's distance.

Write an expression to stand for the time remaining, during which the second driver drove. Follow the same reasoning as above to get an expression for the second driver's distance.

Sum the two "distance" expressions, and set equal to the given total distance. Solve for the variable.

[RyderB]

i still dont get it?

[stapel_eliz]

At which point did you bog down?

Please be complete, so we can "see" where you're having trouble. Thank you!

[kitty2234]

Hi. I needed more practice with this type of problem also. I end up with a bunch of equations. But the equations don't help me to solve the problem. Here are my equations so far: x + y = 490 and x + y = 11.4 hours. And x = 35 and y = 45. And maybe 490 = 35x + 45y. I also made 490 divided by 11.4 hours = 42.98 adverage "WHAT" ?

Not which equations help us to solve the question?

[stapel_eliz]

Here are my equations so far: x + y = 490 and x + y = 11.4 hours. And x = 35 and y = 45. And maybe 490 = 35x + 45y. I also made 490 divided by 11.4 hours = 42.98 adverage "WHAT" ?

You seem to have defined your variables to mean at least three different things. It might help to specify one meaning, and then work from there.

a) Working from the step-by-step instructions provided earlier, what variable have you picked to stand for the time the first driver spent driving?

b) What was the rate of the first driver?

c) Using "d = rt", what expression do you get for the distance that the first driver covered?

Please reply with answers to the above, and then we'll start working on the next step in the instructions.

Thank you!

[kitty2234]

Here are my equations so far: x + y = 490 and x + y = 11.4 hours. And x = 35 and y = 45. And maybe 490 = 35x + 45y. I also made 490 divided by 11.4 hours = 42.98 adverage "WHAT" ?

I need help with this. 2 people drove 490 miles in 11.4 hours. Driver A drove the first part of the trip and averaged 35 mph and Driver B drove the remainder and averaged 45 mph. For what length of time did Driver A drive?

I will try a new method that I have been practicing this morning. I learned it from this site.
d r t
1st driver "x" 490 - y 35 11.4 - y
2nd "y" 490 - x 40 11.4 - x

First equation would be 490 - y = 35(11.4 - y)
490 - y = 399 - 35y

Second equation would be 490 - x = 40(11.4 - x)
490 - x = 456 - 40x

Next equation should be 490 = (490 - y) + (490 - x) + (399 - 35y) + (456 - 40x) I am not sure if I should use the (490-x and the 490-y in this equation.) I wrote this equation is several ways. Is this the correct writing of both equations combined.

[nona.m.nona]

When people try to help you, it might be useful to work with them. What did you get for answers to the questions a, b, and c, just before your last reply?

[kitty2234]

I am not really get any answers for any questions. I am giving you any equation that I can work with. I need to know which equations are really important. My final test is in a few days.