44/9÷1/5＋46/9×5又3/23
=44/9×5＋46/9×5+46/9×3/23
=（44/9+46/9）×5×5+2/3
=10×5+2/3
=50+2/3
=50又2/3
1999/2000*1999
=（1-1/2000）×1999
=1999-1/2000×1999
=1999-1999/2000
=1998又1/2000