\(3 \frac{8}{9} + 2 \frac{11}{18} = 3 \frac{16}{18} + 2 \frac{11}{18} = 5 \frac{27}{18} = 6 \frac{9}{18} = 6 \frac{1}{2}\) т
\(6 \frac{1}{2} - 1 \frac{1}{4} = 6 \frac{2}{4} - 1 \frac{1}{4} = 5 \frac{1}{4}\) т
Ответ: \(5 \frac{1}{4}\) т.