The system of linear equations negative 2 x + y = 8 and -3 x - y = 7 is graphed below.

answer:

step-byx+y=8; x-y=1  

solution :

{x,y} = {9/2,7/2}  

system of linear equations entered :

  [1]     x + y = 8

  [2]     x - y = 1

graphic representation of the equations :

    y + x = 8         y + x = 1  

solve by substitution :

// solve equation [2] for the variable   x  

  [2]     x = y + 1

// plug this in for variable   x   in equation [1]

  [1]     (y +1) + y = 8

  [1]     2y = 7

// solve equation [1] for the variable   y  

  [1]     2y = 7  

  [1]     y = 7/2  

// by now we know this much :

    x = y+1

    y = 7/2

// use the   y   value to solve for   x  

    x = (7/2)+1 = 9/2  

solution :

{x,y} = {9/2,7/2} -step explanation:

susie has 7 apples