SAT Fractions

Number Theory

Daniel ate $\frac{1}{7}$ of a cake. Edward ate $\frac{1}{3}$ of what was left. What fraction of the cake is left uneaten?

(A) $\ \ \frac{1}{7}$

(B) $\ \ \frac{2}{7}$

(D) $\ \ \frac{4}{7}$

(E) $\ \ \frac{6}{7}$