Question 4158
You can't really "solve" equations such as:  x + 4y = 8 or 3x - 5y = 16 unless they are simultaneous (systems of equations) but you can certainly "evalute" them individually, given the additional information, such as possible solution points.

  x + 4y  = 8  for (0, 2)   Substitute 0 for x and 2 for y in the equation.
  0 + 4(2)= 8
        8 = 8  The point (0, 2) is indeed a solution to this equation. 

Similarly:   3x -  5y = 16 for (2, 2)  Again, substitute 2 for x and 2 for y.
          3(2) - 5(2) = 6 - 10 = -4 not = 16 So the point (2, 2) is not a solution.

The next two are evaluated in a similar manner:  

  2x - y = b for (3, 0)   Substitute 3 for x and 0 for y.
2(3) - 0 = b
       6 = b   So, when b = 6, the point (3, 0) is a solution.

   3x  -  2y  = b for (-5, 6)   Substitute -5 for x and 6 for y.
 3(-5) - 2(6) = b
     -15 - 12 = b
         - 27 = b  So, when b = -27, the point (-5, 6) is a solution.