(19又4/9+9又4/19)÷(2又7/9+1又6/19)=(175/9+175/19)÷(25/9+25/19)=[175×(1/9+1/19)]÷[25×(1/9+1/19)]=175÷25=735又9/15×2/17=35又3/5×2/17=(34+8/5)×2/17=34×2/17+8/5×2/17=4+16/85=4又16/85