(3/4一3/16)x(2/9+1/3)=(12/16一3/16)x(2/9+3/9)=9/16×5/9=5/16
(3/4一3/16)x(2/9+1/3)=(12/16-3/16)×(2/9+3/9)=9/16×5/9=5/16
原式=(12/16一3/16)X(2/9十3/9)=9/16X5/9=5/16
=(12/16-3/16)(2/9+3/9)=(9/16)*(5/9)=5/16