If an relationship is proportional what is the missing value from the table?​

Answer : 12

Explanation :

In the first row of the table, we find that the -2 is the change, and in the third row -6 is the change.

Using this, we can find that the second row should have -4 subtracted from 16.

We know this because from looking at the changes from the first and second row, the differences multiply by two, as the rows increase. So -2 multiplied by 2 is -4, and 16 subtract 4 is 12.