# Thread: Kmph to mph question. I didn't know where this should go

1. ## Kmph to mph question. I didn't know where this should go

Can a mod please move this to the appropriate subforum?

Jodie travels at a speed of 80 km per hour for 2 hours 45 minutes. Work out how many miles she drives.

I understand 5 miles = 8 km but I don't know how to solve the question.
Sorry for my noobishness, thanks for the help!

2. ## Re: Kmph to mph question. I didn't know where this should go

(80 km/hr)(2.75 hr) (5 mi/8 km)

?

4. ## Re: Kmph to mph question. I didn't know where this should go Originally Posted by Ashir Can a mod please move this to the appropriate subforum?
Just a quick comment: Algebra is fine for this topic.

-Dan

5. ## Re: Kmph to mph question. I didn't know where this should go

Okay, thanks.

6. ## Re: Kmph to mph question. I didn't know where this should go Originally Posted by skeeter (80 km/hr)(2.75 hr) (5 mi/8 km)
Let's try it by writing it this way.

$\displaystyle \text{80 km/hr} = \frac{80~km}{1~hr}$

So skeeter's line would read:
$\displaystyle \left ( \frac{80~km}{1~hr} \cdot \frac{2.75~hr}{1} \right ) \cdot \frac{5~mi}{8~km}$

The units cancel out in the same way as numbers do. So in the ( ) is the distance the car travels in km. (The units hr cancel out by division.) This comes from the equation d = vt. Then the last factor converts km into miles. In this case the km cancels out.

-Dan

7. ## Re: Kmph to mph question. I didn't know where this should go

...I'll just ask my teacher, thanks though

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