f) $d(d-15)=0$

Step 1 ：Solve the quadratic equation \(d(d-15)=0\) for the variable d.

Step 2 ：\(d = d\)

Step 3 ：\(equation = d(d - 15)\)

Step 4 ：\(solutions = [0, 15]\)

Step 5 ：\(\boxed{Final Answer: The solutions for the equation d(d-15)=0 are d = 0 and d = 15.}\)