4.67-(2.98+0.67)
=4.67-2.98-0.67
=(4.67-0.67)-2.98
=4-2.98
=1.02
73.8x16-73.8x6
=73.8×(16-6)
=73.8×10
=738;
(5分之4+4分之1)÷3分之7+10分之7
=(16/20+5/20)×(3/7)+7/10
=(21/20)×(3/7)+7/10
=9/20+14/20
=23/20;
(1-4分之1-12分之5)÷3分之2
=(1-1/4-5/12)×(3/2)
=(12/12-3/12-5/12)×(3/2)
=(4/12)×(3/2)
=1/2;
9分之8x[7分之3÷(3分之2+7分之1)]
=(8/9)×[(3/7)÷(17/21)]
=(8/9)×(3/7)×(21/17)
=8/17;
18.8-5分之2-5.8-5分之3
=(18.8-5.8)-(2/5+3/5)
=13-1
=12;
3、化简下面各比. 写过程
12.6:0.4=126:4=63:2;
20分之1:6分之5=6:100=3:50;
2分之1吨:450千克=500:450=10:9;
2.5小时:40分=2.5×60:40=150:40=15:4;
4、求未知数X. 写过程.
X:0.25=81:75
75x=81×0.25;
x=81/4×(1/75);
z=81/200;
4分之1:12分之1=8:X
x/4=8/12;
x=8/3;
4X-2.5X=0.75;
1.5x=0.75;
x=0.5;
5.5+3X=8.5
3x=3;
x=1;