Let A be Ravi's age and let B be Ranu's age, we have:
![image](https://img.qammunity.org/2019/formulas/mathematics/middle-school/trcoz0ir3xze3y0wdl5dvgp5ym6lit2c4x.png)
To solve this, we can jsut sub A for 2B and solve for B (which is good since the problem asks for Ranu's age, which is B), so:
![image](https://img.qammunity.org/2019/formulas/mathematics/middle-school/2e7p82rj64tp41njaixzebp4xn4tj5lr7d.png)
We only had to consider the positive solution since age cannot be negative. With that we know that Ranu's age is 6 and Ravi's age is 12.