The answer to your question is 55 :)
2x + 3y = 45
x + y = 10......y = 10 - x
2x + 3(10 - x) = 45
2x + 30 - 3x = 45
-x + 30 = 45
-x = 45 - 30
-x = 15
x = -15 <====
and y = 25
A normal vector is the set of coefficients of x, y, and z when the equation is written in standard (or general) form.
Subtracting the left side, we have
... 2(8 -y) -z +5(x -2) = 0
... 16 -2y -z +5x -10 = 0
... 5x -2y -z +6 = 0 . . . . . general form
A normal vector is (5, -2, -1).
