JAMB 1983 · UME · Q4

Solve the equations $4x - 3 = 3x + y = 2y + 5x - 12$ .

Worked solution (try it first)

Split the chain into two equations.
From $4x - 3 = 3x + y$ , take $3x$ from both sides: $x - y = 3$ .
From $3x + y = 2y + 5x - 12$ , take $2y$ and $5x$ from both sides: $-2x - y = -12$ .
Multiply by $-1$ : $2x + y = 12$ .
Add the two equations so $y$ cancels: $3x = 15$ , so $x = 5$ .
Then $y = x - 3 = 2$ .
So $x = 5$ , $y = 2$ , option A.