[latex] \frac{7}{9} * (1,8 - 2,7) + 0,6(2-3a)[/latex] если [latex]a = - 1 \frac{7}{8} [/latex].

[latex] \frac{7}{9} \cdot(1.8 - 2.7) + 0.6(2-3a)= \frac{7}{9} \cdot(-0.9)+ 1.2-1.8a= \\\ = 7 \cdot(-0.1)+ 1.2-1.8a=-0.7+ 1.2-1.8a=0.5-1.8a=0.5- \\\ -1.8\cdot (-1 \frac{7}{8} )= \frac{1}{2} - \frac{18}{10} \cdot (- \frac{15}{8} )= \frac{1}{2} + \frac{18\cdot15}{10\cdot8} =\frac{1}{2} + \frac{9\cdot3}{2\cdot4} = \frac{4}{8} + \frac{27}{8} = \frac{31}{8} [/latex]