[tex]1-( \frac{3}{20} +2 \frac{11}{20} )=-1 \frac{7}{10} \\ \\ 1) \frac{3}{20} +2 \frac{11}{20} =2 \frac{7}{10} \\ \\ \frac{3*1}{20} +2 \frac{11*1}{20} =2 \frac{3+11}{20} =2 \frac{14}{20} =2 \frac{7}{10} \\ \\ 2 \frac{14}{20} =2 \frac{2*7}{2*2*5} =2 \frac{7}{10} \\ \\ 2) 1-2 \frac{7}{10} =-1 \frac{7}{10} [/tex]