hi i have a problem

Question

i have: 

2c+6u=24

4c+6u=36

 can you tell me step by step how to solve this? i have tried and i can not get any whole numbers. i have no idea what i'm doing. thank you. 

Answer 1

2c+6u=24
4c+6u=36

 

Both equations contain a 6u term.  Let's use that to eliminate the u terms and solve for c.  let's multiply the first equation by -1 then add it to the second equation to eliminate the u variable:

 

 -2c - 6u = -24

+4c + 6u = 36

-----------------

  2c + 0  = 12

 

2c = 12

 

c=6

 

To find u. plug c=6 into either equation and solve for u:

 

2c + 6u = 24

2(6) + 6u = 24

12 + 6u = 24

6u = 12

 

u = 2

 

Check:

2c + 6u = 24

2(6) + 6(2) = 24

12 + 12 = 24

24 = 24    CHECK!

 

4c + 6u = 36

4(6) + 6(2) = 36

24 + 12 = 36

36 = 36     CHECK!

 

Answer 2

Hi Crystal,

 

2c+6u=24
4c+6u=36

          

The way to start is to eliminate one of the variables by performing valid operations to maintain the equalities.

So lets start by subtracting the first equation from the second (this eliminates the variable u) and gives

 

2c=12, solving for c gives c=6. Putting this value for c into either equation and solve for u i.e.2*6+6u=24 or u=2

 

So c=6, u=2 is the solution.

 

Hope this helps

 

Jim