= 21/17*(2+2/3-3/4)+(17+11/12)*21/17 =21/17*(2+2/3-3/4+17+11/12) =21/17*(2+8/12-9/12+17+11/12) =21/17(2-1/12+17+11/12) =21/17(2+17+10/12) =21/17(19+5/6) =21/17*119/6 =(3*7/17)*(17*7/3*2) =49/2
