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May 30th, 2014, 06:24 AM   #11
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Quote:
Originally Posted by weirddave View Post
If they are making 3 add-ons, then the time to make 1 of each is all that's required, then just copy it
precisely why the question should be re-written.
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May 31st, 2014, 09:13 AM   #12
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Hmmm...Todd told us this:
"I'm a chef for 20 years and now attending school for Hospitality and Restaurant Management. I use to love
math in high school. I am just now getting reintroduced to Algebra and would appreciate any help I could get."

I don't think exotic solving ways is what he wants/needs; just sufficient to help him pass that HRM course.

Using Greg's approach (my favorite!):
9A + 10B + 12C = 398 [1]
6A + 4B + 4C = 164 [2]
A + 2B + C = 58 [3]
Using elimination of variables, it can readily be determined that A = 6, B = 20 and C = 12.

I'm pretty sure Todd wants to "remember" how above is accomplished.

The easiest variable to eliminate first is C (2 multiplications only);
multiply [2] by 3 and [3] by 12, and we now have:
09A + 10B + 12C = 398 [1]
18A + 12B + 12C = 492 [2]
12A + 24B + 12C = 696 [3]

Subtract [1] from [2]:
9A + 2B = 94 [4]
Subtract [1] from [3]:
3A + 14B = 298 [5]
Multiply [5] by 3:
9A + 42B = 894 [5]

Subtract [4] from [5]:
40B = 800 : so B = 800/40 = 20

Now you can go back and substitute B=20; let's take [4]:
9A + 2(20) = 94
9A + 40 = 94
9A = 54
A = 6

Now pick one of [1],[2],[3] and substitute A=6 and B=20 to get C : all yours to try!
Thanks from Benit13

Last edited by Denis; May 31st, 2014 at 09:17 AM.
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June 4th, 2014, 03:07 AM   #13
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Math Focus: Physics, mathematical modelling, numerical and computational solutions
Quote:
Originally Posted by Denis View Post
I don't think exotic solving ways is what he wants/needs; just sufficient to help him pass that HRM course.

Using Greg's approach (my favorite!):
9A + 10B + 12C = 398 [1]
6A + 4B + 4C = 164 [2]
A + 2B + C = 58 [3]
Using elimination of variables, it can readily be determined that A = 6, B = 20 and C = 12.
I agree. Matrix methods are sexier and cleaner, but certainly not easier to do or understand. Use elimination of variables until you learn matrices (which I recommend by the way, they're awesome).
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