I know this is easy but I just can't seem to find the answer. a+b=26 b+c=36 What is a+b+c?

Question

I've been trying to solve this equation but I just seem to be missing something. 

Answer 1

First, notice that you do not need to determine the individual values of a, b, and c.  That simplifies the problem.

Next, notice that b appears in both equations, but a and c do not.  This means that solving for b and substituting might help us.

Then, try to break apart (a+b+c) so that you may use (a+b) and (b+c) to find the desired sum:
   a+b+c = (a+b) + (b+c) - b

              =  26     +   36   - b

              = 62 - b

 

That helps, but it we need another constraint (that is, another equation) to limit the possible values.

 

Here are a few of the values that satisfy the two equations:

  a     b     c        a+b+c

  1    25   11          37

  2    24   12          38

  3    23   13          39

  4    22   14          40

. . .

 

[note: you must determine whether to include non-integers, zero and negative values.]

Answer 2

a+b=26

 

a=26-b

 

b+c=36

 

c=36-b

 

 

=a+b+c

 

=26-b+b+36-b

 

=62-b