SAT Math · Linear equations in one variable · medium

What is the value of x if (4x-3)/(7) + 2 = 9?

What is the value of xx if 4x−37+2=9\dfrac{4x-3}{7} + 2 = 9?

Answer and explanation

Answer: D: 13

Undo the operations in reverse order. Subtract 2 from both sides of 4x−37+2=9\frac{4x - 3}{7} + 2 = 9: 4x−37=7\frac{4x - 3}{7} = 7. Multiply by 7: 4x−3=494x - 3 = 49. Add 3: 4x=524x = 52. Divide by 4: x=13x = 13, choice D. Check: 4(13)−37+2=497+2=9\frac{4(13) - 3}{7} + 2 = \frac{49}{7} + 2 = 9. Choice A (11) gives 417+2≈7.9\frac{41}{7} + 2 \approx 7.9. Choice B (15) gives 577+2≈10.1\frac{57}{7} + 2 \approx 10.1. Choice C (9) gives 337+2≈6.7\frac{33}{7} + 2 \approx 6.7. None satisfies the equation, so back-substitution quickly rules them out.

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