1)[tex] =\frac{10+9}{12}* \frac{24}{19} = \frac{24}{12}=2 \\ 2) =\frac{6+28}{36}* \frac{18}{17} = \frac{34}{2}=17 \\ 3) =\frac{15-6}{36}*4= \frac{9}{36}*4 =1 \\ 4) =\frac{22-3}{90} * \frac{18}{19}= \frac{19}{90}* \frac{18}{19}= \frac{18}{90}= \frac{1}{5} [/tex]