$$2\frac{26}{27}- \frac{39}{45} = 2\frac{26}{27}- \frac{13}{15} = 2\frac{26\cdot5}{27\cdot5}- \frac{13\cdot9}{15\cdot9} = 2\frac{130}{135}- \frac{117}{135} = 2\frac{13}{135}$$
Ответ: $$2\frac{13}{135}$$