Solve. For Exercises 83 and $84,$ see the second Concept Check in this section, for Exercises 85 and $86,$ see the third Concept Check.
Which of the expressions are equivalent to $\frac{x}{5-x} ?$
a. $\frac{-x}{5-x}$
b. $\frac{-x}{-5+x}$
c. $\frac{x}{x-5}$
d. $\frac{-x}{x-5}$