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Im a developer working on some veterinary calculators,

I have found all the required equation substitutions needed for my app, but I left the last one for now and is giving me a bit of a doubt filled mind…

Is a simple two linear equations solved by substitution method,

I have::

AB = CD
E = D-B

I need to find B and D…

Any ideas? Is simple, high school stuff, but I have forgotten a bit

thanks a lot!

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1 Answer 1

up vote 1 down vote accepted

You have: $AB = CD$ and $E = D-B$.

Divide the first equation by $A$: $B = \frac{CD}{A}$, and substitute into the second.

This yields $E = D - \frac{CD}{A} = D(1-\frac{C}{A})$. Therefore $D = \frac{E}{1-\frac{C}{A}}$.

Finally backsubstitute to get $B = \frac{C}{A}\frac{E}{(1-\frac{C}{A})} = \frac{CE}{A-C}$

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thanks a lot! i have to practice solving equations! have a great day! –  MaKo Oct 3 '12 at 6:02

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