Word Problem: You want to burn 380 calories during 40 minute

J

JMM90

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Sep 28, 2006
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Could you help me get started on this word problem:

You want to burn 380 calories during 40 minutes of exercise. You burn about 8 calories per minute inline skating and 12 calories per minute swimming. How long should you spend doing each activity?
 
K = Time Skating
W = Time Swimming

That is 70% of the problem. You do the other 30%.
 
I had x = skating and y= swimming
so I took
8x + 12y =380
but where do I put the 40 minutes and how do I figure it?
 
JMM90 said:
I had x = skating time and y= swimming time
so I took
8x + 12y =380
but where do I put the 40 minutes and how do I figure it?
Click to expand...

You know this, right?

time skating + time swimming = 40 minutes
x + y = 40

Ok...now you have two equations:

8x + 12y = 380
x + y = 40

NOW can you finish? (hint: you can solve the second equation for x: x = 40 - y Then substitute 40 - y for x in the first equation)
 
Don't get hung up on X and Y. Try to pick things that are meaningful. Trust me on this. If you ALWAYS have to refer to your definition to tell what it is you are talking about, that can't be good.

I had x = skating and y= swimming
Click to expand...
See, you already had started. Good work.
 
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