Truthfully? Since it isn't possible to do what you have suggested, you may wish to review what it is you have been asked to do.
Can you supply the COMPLETE problem statement rather than your abbreviated version?
Ok here's the whole question:
In an experiment, sets of values of the related variables (x,y,) are obtained. State how you would determine whether x and y were related by a law of the form:
(a)
(b)
where in each case, a and b are unknown constants. State briefly how you would be able to determine the values of a and b for each law.
So you have (from the experiment) a set of values of x and the corresponding values for y. In (b), you want to know whether x and y are related by an equation of the form , where a and b are constants. Write the equation in the form . That suggests that you should put . For each pair of values (x,y), calculate the corresponding value of z. Then plot a graph of z against x. Hopefully the points will look as though they lie on a straight line, with equation az = x+b.