Algebra practice question

Answer: B. 5

Subtract 7 from both sides: 3x = 15. Divide by 3: x = 5. Choice D is the value of 3x — a classic 'stopped one step early' trap.

Why the other answers are wrong

A. 3

3 is the coefficient of x, not its value — after subtracting 7 you get 3x = 15, and you still need to divide both sides by 3.

C. 7

7 is the constant already in the equation; substituting x = 7 gives 3(7) + 7 = 28, not 22.

D. 15

You correctly got 3x = 15 but stopped there — divide both sides by 3 to get x = 5.

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