SAT Question a1fd2304: Linear Equations In Two Variables answer and explanation with Desmos solution

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 $3\times 0.10$, $x\times 0.25$, and $(x+3)\times 0.15$, 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 $3\times 0.10+0.25x=0.15\times (x+3)$ must be true. Multiplying $3$ by $0.10$ and distributing $0.15$ to $(x+3)$ yields $0.30+0.25x=0.15x+0.45$. Subtracting $0.15x$ and $0.30$ from each side of the equation gives $0.10x=0.15$. Dividing each side of the equation by $0.10$ yields $x=1.5$. Note that 3/2, 1.5, and 1.50 are examples of ways to enter a correct answer.