If a+b = 11, b+c = 15, and a+c =10, what is the value of a+b+c?

I know we have 3 equations in two unknowns.

Can someone show how to find one of the variables?

I can then proceed to find the other two.

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- Dec 10th 2018, 04:23 PM #1

- Dec 10th 2018, 04:39 PM #2

- Dec 11th 2018, 04:46 AM #3

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- Dec 11th 2018, 06:24 AM #4

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## Re: a + b + c

Since I'm not nearly as smart as Halls, I'd do it this way (which is the best way!):

a+b = 11 [1]

b+c = 15 [2]

a+c = 10 [3]

Code:a + b = 11 [1] -a - c = -10 [3]*-1 ============ b - c = 1 b + c = 15 [2] ============ 2b = 16 b = 16/2 = 8

3 cheers fer me!!

- Dec 11th 2018, 06:33 AM #5

- Dec 11th 2018, 06:45 AM #6
## Re: a + b + c

**@ harpazo,**In the testing business this question is known as an "eater". There are two ways to do.

One is to solve for $a,~b,~\&~c$ so to be able find the value of $a+b+c.$ That eats up time, so the name.

The other as I used really requires only simple addition & division. From other posts I know you are preparing for tests.

- Dec 11th 2018, 09:47 AM #7

- Dec 11th 2018, 09:49 AM #8

- Dec 11th 2018, 10:09 AM #9

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- Dec 11th 2018, 06:25 PM #10

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- Dec 11th 2018, 06:59 PM #11
## Re: a + b + c

On set of all people the relation $\mathscr{S}$ defined as $\mathscr{S}(A,B)\iff A\text{ is smarter than }B$ is

- irreflexive
- asymmetric
- transitive

I can absolutely assure that $(plato,HallsofIvey)\notin\mathscr{S}$ that said the jury is out on if $(HallsofIvey,plato)\in\mathscr{S}~.$

- Dec 11th 2018, 08:07 PM #12

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- Dec 11th 2018, 11:13 PM #13

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- Dec 12th 2018, 05:54 AM #14

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## Re: a + b + c

- Dec 12th 2018, 02:43 PM #15

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