H+j + 2k = 16
4h + 4j + 2k = 5
2h + 2j + k = 31

Answer and explanation:

h

Subtract h + j + 2k = 16 by 4h + 4j + 2k = 5

    h + j + 2k = 16

-(4h + 4j + 2k = 5)

  -3h - 3j = 11    Then add 3j to both sides to get -3h alone

  -3h = 11 + 3j   Now divide both sides by -3 to get h

     h = =

j

Plug in h and k to h + j + 2k = 16 ---> + j + 2(1) = 16

Then add any like terms together + 2j = 16

Add on both sides 2j = + 16

Divide both sides by 2

You can divide a fraction by a fraction, so you do kcf  j = · =

k

Multiply h + j + 2k = 16 by 2 --->  2h + 2j + 4k = 32

Then subtract 2h + 2j + 4k = 32 by 2h + 2j + k = 31

  2h + 2j + 4k = 32

 -(2h + 2j + k = 31)

                  3k = 1  Divide both sides by 3 to get k

                    k = 1

According to Wikipedia: "In mathematics, a function is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output."

So based of this we need to look for a set where one of the x values or the y values is the same, and the other number is different.

B.
(1,4) and (1,1) both have the same x, but different y!