Since (8,4) is an element of the solution set of , there are an infinite number of answers to this problem (if (8,4) had NOT been an element of the solution set of , there would be no solutions). Follow the procedure to determine as many of them as you like.
Pick any value you like for , then use the point-slope form of an equation of a line:
Substituting 8 and 4 for and .
Solve for in terms of everything else putting your equation into form. Determine the to go with your chosen by inspection. Repeat as often as pleases you with as many real number selections for that you like.
My calculator said it, I believe it, that settles it