Question

[-1,2(5) + 0.1(4)] × [12 - 1.1(5) - 1.8(4)] = ?

Answer 1

$[-1,2(5) + 0.1(4)] * [12 - 1.1(5) - 1.8(4)] = \\ \\ (-1\frac{25-2}{90} + \frac{14-1}{90} )*(12- 1\frac{15-1}{90}-1 \frac{84-8}{90} )= \\ \\ (-1 \frac{23}{90} + \frac{13}{90} )*(12- 1\frac{14}{90} -1 \frac{76}{90} )= \\ \\ (- \frac{113}{90} + \frac{13}{90} )*( \frac{1080}{90} - \frac{114}{90} - \frac{166}{90} )= \\ \\ -\frac{100}{90}* \frac{800}{90}= \\ \\ -\frac{10}{9} * \frac{80}{9} = \\ \\ =\frac{800}{81}$