Question

[-1,2(5)+0,1(4)]x[12-1,1(5)-1,8(4)]=

Answer 1

$\displaystyle [-1,2(5)+0,1(4)]\cdot[12-1,1(5)-1,8(4)]= \\ \\ =\left(- \frac{125-12}{90} + \frac{14-1}{90} \right) \cdot \left(12- \frac{115-11}{90} - \frac{184-18}{90} \right )= \\ \\ =\left(- \frac{113}{90} + \frac{13}{90} \right ) \cdot \left(12- \frac{104}{90} - \frac{166}{90} \right )= \\ \\ =- \frac{100}{90} \cdot \left( \frac{1080}{90} - \frac{104}{90} - \frac{166}{90} \right)=- \frac{100}{90} \cdot \frac{810}{90} =- \frac{81000}{8100} =-10$