Algebra practice question

Answer: 10

Add 1.2 to both sides: 0.4x = 4. Divide by 0.4: x = 10. Check: 0.4(10) − 1.2 = 4 − 1.2 = 2.8.

Common wrong answers

If you answered 4

4 is 0.4x, one step short. Divide by 0.4 to get x = 10.

If you answered 7

7 comes from 0.4x = 1.6 (2.8 − 1.2), subtracting the 1.2 instead of adding it. The −1.2 moves across as +1.2.

If you answered 1.6

1.6 is 4 × 0.4, multiplying by 0.4 instead of dividing.

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