399x398
=(400-1)(400-2)
=160000-1200+2
=158802
1/3x9/20÷（1+1/2)
=3/20x2/3
=1/10
0.2:1.6
=1:8
1/4:0.3
=5:6
0.25:0.75
=1:3
24:36
=2:3
2:0.58
=100:29
9/10:1/4
=18:5
20.5吨：125千克
=162:1你再教我4个，我采纳你行不 。解方程4/5x+1/2x=13 2.5x+5/6乘以12=61.6x+6=10+2/5x3x=50-7÷7÷1/24/5x+1/2x=1313/10x=13x=10 2.5x+5/6乘以12=62.5x=-4x=-8/5 1.6x+6=10+2/5x1.2x=4x=10/33x=50-7÷7÷1/23x=48x=16