Answer :
[tex]d=f+fx\\\\f+fx=d\ \ \ \ |subtract\ f\ from\ both\ sides\\\\fx=d-f\ \ \ \ \ |divide\ both\ sides\ by\ f\\\\\boxed{x=\frac{d-f}{f}}\\\\other\ answer:\ x=\frac{d-f}{f}=\frac{d}{f}-\frac{f}{f}\\\boxed{x=\frac{d}{f}-1}[/tex]
