Choice A is the correct answer. Decimals follow the same rules as whole numbers.

1. Subtract 0.9x: $1.5x - 0.9x + 2.4 \leq 6$, giving $0.6x + 2.4 \leq 6$
2. Subtract 2.4: $0.6x \leq 3.6$
3. Divide by 0.6: $x \leq 6$

?�� Strategic Tip: Alternatively, multiply everything by 10 to eliminate decimals: $15x + 24 \leq 9x + 60$.

Choice B is incorrect because it reverses the direction without cause. Choice C is incorrect because it might come from dividing 2.4 by 0.6 without subtracting first. Choice D is incorrect because it combines wrong value and wrong direction.