SAT Mathematics Practice Test 4

The equation $\frac{\mathit{a}-\mathit{b}}{\mathit{b}}=\frac{3}{7}$ can be rewritten as $\frac{\mathit{a}}{\mathit{b}}-\frac{\mathit{b}}{\mathit{b}}=\frac{3}{7}$, from which it follows that $\frac{\mathit{a}}{\mathit{b}}-1=\frac{3}{7},$ or$\frac{\mathit{a}}{\mathit{b}}=\frac{3}{7}+1=\frac{10}{7}$.Choices A, C, and D are incorrect and may be the result of calculation errors in rewriting $\frac{\mathit{a}-\mathit{b}}{\mathit{b}}=\frac{3}{7}$For example, choice A may be the result of a sign error in rewriting $\frac{\mathit{a}-\mathit{b}}{\mathit{b}}$ as $\frac{\mathit{a}}{\mathit{b}}+\frac{\mathit{b}}{\mathit{b}}=\frac{\mathit{a}}{\mathit{b}}+1$