Linear equations in two variables SAT question

The correct answer is 1.5. The total amount, in liters, of a saline solution can be expressed as the liters of each type of saline solution multiplied by the percent concentration of the saline solution. This gives , , and , where x is the amount, in liters, of 25% saline solution and 10%, 15%, and 25% are represented as 0.10, 0.15, and 0.25, respectively. Thus, the equation must be true. Multiplying 3 by 0.10 and distributing 0.15 to yields . Subtracting 0.15x and 0.30 from each side of the equation gives . Dividing each side of the equation by 0.10 yields . Note that 1.5 and 3/2 are examples of ways to enter a correct answer.