1,
a,
=<21/8+4/8>:5/16
=25/8:5/16
=5/128
b,
= (32,5 + 76,41 - 108,91) x 2020
= 0 x 2020
= 0
c,
=136*75+75*68-75*4
=75*<136+68-4>
=75*200
=15000 *là phép nhân nha , / la pân số
d,
=135*1420+4,5*780*3/3+6+9+...+24+27
=135*1420+13,5*780/<3+7>+<6+24>+<9+21>+<21+18>+15
=135*<142+78>/30*4+15
=135*220/135
=220
2,
a,2/3.x+3/4=3
=>2/3.x=3-3/4
=>2/3.x=9/4
=>x=9/4:2/3
=>x=9/4.3/2
=>x=27/8
b,0,2:x=1,03+3,97
=>0,2:x=5
=>x=0,2:5
=>x=0,04
c, 720:[41-(2.x-5)]=120
=>41-(2.x-5)=720:120
=>41-(2.x-5)=6
=>(2.x-5)=41-6
=>(2.x-5)=35
=>2.x-5=25
=>2.x=25+5
=>2.x=30
=>x=15
d,(2/1x3 +2/3x5 +2/5x7 +2/7x9 +2/9x11)x X=2/3
=>(2/1+2/3+2/3+2/5+2/5+2/7+2/7+2/9+2/9+2/11)x X=2/3
=>(2/1+2/11)x X =2/3
=>24/11x X=2/3
=>x=2/3:24/11
=>x=22/72
=>x=11/36
=> tức là suy ra nha
