Question

what is the value of c?

Given:

a+b=c

a-c=5

b-c=3

Answer 1

Given:        a + b = c     ,      a - c = 5     ,      b - c = 3

 

So we just need to rearrange the equations.

 

Let's start with  a - c = 5

Add c to both sides of the equation,

a = 5 + c

 

Now let's rearrange  b - c = 3 by adding c to both sides of the equation,

b = 3 + c

 

Now we can subtitute both these equations into the equation   a + b = c

(5 + c) + (3 + c) = c

5 + 3 + c + c = c

8 + 2c = c

Subtract c from both sides of the equation,

8 + 2c - c = c - c

8 + c = 0

Now subtract 8 from both sides of the equation,

So,   c = - 8                       

 

If you need to you can now use the equations   a - c = 5  ,  b - c = 3  , to find the values of a and b.

 

If you need help doing this last stage feel free to ask.