Đáp án:
`\frac{3}{8} - (\frac{18}{45} - \frac{19}{51} - \frac{3}{11})`
`= \frac{3}{8} - (\frac{7}{255} - \frac{3}{11})`
`= \frac{3}{8} - \frac{-688}{2805}`
`= \frac{3}{8} + \frac{688}{2805}`
`= \frac{8415}{22440} + \frac{5504}{22440}`
`= \frac{13919}{22440}`
Chúc học tốt!!!