The tree grows 6cm per year and we need to find out how long it will take to grow 1 meter. We know that 1 meter is equal to 100 centimeters. So:
6x = 100
x = 16.67
It will take 16.67 years (or one and two-thirds of a year) for the tree to reach 1 meter.
What you would do is you would substitute each ordered pair into their respective variables. (ie. for (0,1) you would put 0 where the x is and 1 where the y is) You would then solve the equation. If the equation is not even (ie. 2=5 would not be even but 4=4 would be), you move on to the next ordered pair.
If you follow the process right and you get the equations correct, the answer should be B. (7,-2)