The answer is c. 0.10. Week 4 is plotted at 0.35 and Week 2 is plotted at 0.25. Difference means subtract. 0.35 - 0.25 = 0.10. Hope this helps!
Just put the coefients in to a matrix
1x-6y-3z=4
-2x+0y-3z=-8
-2x+2y-3z=-14
mulstiply 2nd row by -1 and add to 3rd
divde last row by 2
multiply 2rd row by 6 and add to top one
multiply 1st row by -1 and add to 2nd
divide 2nd row by -3
mulstiply 2nd row by -1 and add to 1st row
divide 1st row by -3
rerange
x=-2
y=-3
z=4
(x,y,z)
(-2,-3,4)
B is answer