WAEC 2020 · Paper 1 · Q10

Linear & simultaneous equations

Solve $3x - 2y = 10$ and $x + 3y = 7$ simultaneously.

Worked solution (try it first)

Make $x$ the subject of the second equation: $x = 7 - 3y$ .
Substitute into the first: $3(7 - 3y) - 2y = 10$ , so $21 - 11y = 10$ .
Take 21 from both sides: $-11y = -11$ , so $y = 1$ .
Then $x = 7 - 3 = 4$ .
So $x = 4$ and $y = 1$ , option D.

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