We are asked to determine the cost of a desktop computer and a laptop computer.
Let "x" be the cost of the desktop computer and "y" be the cost of the laptop computer.
We are given that the laptop costs $300 more than the desktop, therefore, we have:

Now, we are also given that the total interest paid for both computers is $365.
We have:

Where:

Now, since the interest paid for the desktop is 9%, we have that it must be equal to:

The interest paid for the laptop is 7%, therefore, it must be:

Now, we substitute in the equation for the total interest paid:

We get two equations and two variables. To solve the system we will substitute the value of "y" from equation (1) into equation (2):

Now, we apply the distributive law on the parenthesis:

Now we add like terms:

Now, we solve for "x", first by subtracting 21 from both sides:

Now, we divide both sides by 0.16:

Solving the operations:

Now, we plug in the value of "x" in equation (1):

Therefore, the cost of the desktop is $2150 and the cost of the laptop is $2450.