Algebra practice question

Answer: 3

Substitute y = 2x − 1 into the second equation: 3x + (2x − 1) = 14, so 5x − 1 = 14, giving 5x = 15 and x = 3. Substitution shines when one variable is already isolated.

Common wrong answers

If you answered 5

That's the value of y (2·3 − 1 = 5). The question asks for x, which is 3.

If you answered 15

That's 5x, not x — you stopped one step early and still need to divide 15 by 5.

If you answered 2.6

You substituted but flipped the sign of the −1: 3x + (2x − 1) gives 5x − 1 = 14, not 5x + 1 = 14.

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