DOUBT IN MANHATTAN QUANT QUESTION

If x = (9b - 3ab)/(3/a - a/3), what is x? (1) 9ab/(3+a) = 18/5 (2) b = 1 This question is present in Manhattan guide 2 in chapter Strategy:Combos. It's official answer is A. However I have doubt in that. In the official Manhattan guide explanation the equation is reformed into 3a(3b)(3-a)/(3-a)(3+a)...