David S. answered • 08/27/16
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CMU Grad to Help You Get the Big Ideas + Little Things in Science/Math
Taylor,
What level of math are you in right now? It sounds like an Algebra 1 type of exercise. There are many ways to do this type of problem so having a little background would be helpful so that we're not shooting way over your head with our replies. [OK see my answer below in the comment section... I'm still new to using this properly : )]
David S.
tutor
OK great! Set up two equations with the two things you don't know each given their own variable, then solve them together -- called a solving a system of equations or simultaneous equations.
You know that a nickel is worth 5 cents (or 0.05 dollars) and a dime 10 cents (or 0.10 dollars). I say this first because the units you choose can make the problem more cumbersome than needed. In this case I'd rather stick with integers since I know that I can only have integer values for the quantities of nickels and dimes in the end or else something very strange has occurred along the way!
So the first equation could look like this:
5n + 10d = 945 (remember we're working in cents for the money values)
The next is just doubling the dimes quantity so:
5n + 10(2d) = 1665 which I hope is self-evident from what I wrote above.
Do a little simplifying and then subtract the first equation from the second and you should see something like:
10d = 720 which should be pretty easy to figure out how many dimes you originally had.
Take the value for d and substitute it into either of the two equations to let you solve for n and you should be all set.
Hope this helps.
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08/27/16
Taylor P.
08/27/16