Question

Solve for x and y: x-3y=-8 3x+2y=31

Answer 1

 x = 3y - 8

Plug this in for variable  x  in equation [2]
  [2] 3•(3y-8) + 2y = 31   [2] 11y = 55

 Solve equation [2] for the variable  y  

  [2] 11y = 55    [2] y = 5 

// By now we know this much :

  x = 3y-8   y = 5

// Use the  y  value to solve for  x  

  x = 3(5)-8 = 7 Solution : {x,y} = {7,5}  Processing ends successfully

Answer 2

x - 3y = -8
3x + 2y = 31
———————
3x - 9y = -24
3x + 2y = 31
———————
-11y = -55
y = 5

x - 3y = -8
x - 3(5) = -8
x - 15 = -8
x = 7

(x, y) = (7, 5)