JAMB 2016 · UTME · Q36

If $2x + 3y = 1$ and $x - 2y = 11$ , find $(x + y)$ .

Worked solution (try it first)

Make $x$ the subject of the second equation: $x = 11 + 2y$ .
Substitute into the first: $2(11 + 2y) + 3y = 1$ , so $22 + 7y = 1$ and $y = -3$ .
Then $x = 11 - 6 = 5$ .
So $x + y = 5 + (-3) = 2$ , option D.