So for any question where you need to write your own equation, it is first necessary that you determine what each number in the problem means in order to determine where they should go. James has $65 so the equation needs to be set equal to 65. The problem says he wants to buy a DVD for $23 so that would be a constant $23 spent regardsless of how many CDs he buys. We are trying to use the equation to determine how many CDs James can buy so the number of CDs is the x value at $14 each which would be 14x in the equation. so the equation would be the 14x for the unknown number of CDs, plus 23 for the constant DVD that James would buy set equal to the $65 he can use to buy everything.
To solve the equation, you must now isolate for x. To start, cancel out the +23 on the left side by subtracting 23 from both sides. This will leave 14x=42. You must then cancel the 14 by dividing both sides by 14 leaving your answer of x=3CDs.