(1) 3又1/4×15又2/3-1.25×15又2/3
=(3又1/4-1又1/4)×15又2/3
=2×15又2/3
=31又1/3
(2)3-4/5÷1/3-2/5
=3-4/5×3-2/5
=3-12/5-2/5
=(15-12-2)/5
=1/5
(3)9又9/20÷【(5/6-3/12)×24】
=9又9/20÷(7/12×24)
=189/20÷14
=27/40
(1) 3又1/4×15又2/3-1.25×15又2/3
=(3又1/4-1又1/4)×15又2/3
=2×15又2/3
=31又1/3
(2)3-4/5÷1/3-2/5
=3-4/5×3-2/5
=3-12/5-2/5
=(15-12-2)/5
=1/5
(3)9又9/20÷【(5/6-3/12)×24】
=9又9/20÷(7/12×24)
=189/20÷14
=27/40