Algebra practice question

Answer: 5

Expand: 6x + 3 − x = 7x − 7, so 5x + 3 = 7x − 7. Subtract 5x: 3 = 2x − 7. Add 7: 2x = 10, x = 5. Check: 3(11) − 5 = 28 and 35 − 7 = 28.

Common wrong answers

If you answered 2

2 comes from 6x + 3 = 7x − 7 → x = 10, or from dropping terms; check: 3(5) − 2 = 13 but 14 − 7 = 7.

If you answered 10

10 comes from forgetting the −x on the left: 6x + 3 = 7x − 7 gives x = 10, but the equation has 5x on the left.

If you answered -2

−2 comes from 5x + 3 = 7x + 7 (the −7 turned into +7).

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