SAT Mathematics Practice Test 4

If $\mathit{f}\left(\mathit{x}\right)=-2\mathit{x}+5,$ then one can evaluate $\mathit{f}\left(-3\mathit{x}\right)$ by substituting −3x for every instance of x. This yields $\mathit{f}\left(-3\mathit{x}\right)=-2\left(-3\mathit{x}\right)+5,$ which simplifies to $6\mathit{x}+5.$
Choices A, C, and D are incorrect and may be the result of miscalculations in the substitution or of misunderstandings of how to evaluate $\mathit{f}\left(-3\mathit{x}\right).$