(7/10+5/6+4/5)*30=,(5/6--5/8)*24=,121*100又121分之1=,5又4分之3*0.4+2/5*4.25=,2.7*2

(7/10+5/6+4/5)*30=,(5/6--5/8)*24=,121*100又121分之1=,5又4分之3*0.4+2/5*4.25=,2.7*2.75+6.3*2.

解: (7/10+5/6+4/5)X30=21+25+24
=70.
(5/6--5/8)X24=20--15
=5.
121X100又121分之1=121X12101/121
=12101.
5又4分之3X0.4+2/5X4.25=5.75X0.4+0.4X4.25
=0.4X(5.75+4.25)
=0.4X10
=4.
2.7X2.75+6.3X2.75+2又4分之3=2.7X2.75+6.3X2.75+2.75
=2.75X(2.7+6.3+1)
=2.75X10
=27.5.
3又4分之1X4又5分之3--4.6X2又4分之1=3.25X4.6--4.6X2.25
=4.6X(3.25--2.25)
=4.6X1
=4.6.
6又2分之1X3/5+3.5/1又3分之2=6.5X3/5+3.5X3/5
=3/5X(6.5+3.5)
=3/5X10
=6.
(420/30)X(14/25)+(14/25)X86=14X(14/25)+(14/25)X86
=14/25X(14+86)
=14/25X100
=14X4
=56.

（7/10+5/6+4/5）*30=7*3+5*5+4*6=70
（5/6--5/8）*24=5*4-5*3=5
121*100又121分之1=121*(100+1/121)=12100+1=12101
5又4分之3*0.4+2/5*4.25=(5又4分之3+4.25)*0.4=10*0.4=4
2.7*2.75+6.3*2.75+2又4分之3=2.75*(2.7+6.3+1)=2.75*10=27.5
3又4分之1*4又5分之3--4.6*2又4分之1=(3又4分之1-2又4分之1)*4.6=1*4.6=4.6
6又2分之1*3/5+3.5/1又3分之2=6又2分之1*3/5+3.5/3分之5=6又2分之1*3/5+3.5*3/5=(6又2分之1+3.5)*3/5=10*3/5=6
420/30*14/25+14/25*86=(420/30+86)*14/25=(14+86)*14/25=4*14=56