1 фото:
1,2-(2,6+2 1/5):2 2/3=6/5-(13/5+11/5):8/3=6/5-24/5:8/3=6/5-24/5*3/8=6/5-9/5=-3/5
а)2/7*(7а-14)-2/5*(10-5а)=2а-2-4+2а=4а-6
б)-(-5,2-3,1t)-(2,4t-6,4)=5,2+3,1t-2,4t+6,4=11,6+0,7t
2 фото:
1+0,15:(11/12-0,75)=1+15/100:(11/12-75/100)=1+3/20:(11/12-15/20)=1+3/20:(220/240-180/240)=1+3/20:40/240=1+3/20*240/20=1+36=37
3(5m-4n)-4(3m-2n)=15m-12n-12m+8n=3m-4n
3*(-0.2)-4*0.7=-0.6-2.8=-3.4
3 фото:
(8 7/12-2 17/36)*2,7-4 1/3:0,65=(103/12-89/36)*27/10-13/3*20/13=(309/36-89/36)*27/10-20/3=220/36*27/10-20/3=66/4-20/3=198/12-80/12=118/12=59/6=9 5/6
а)3/4(х+2)+2/5(х-1)=21/40
3/4х+6/4+2/5х-2/5=21/40
3/4х+2/5х=21/40-6/4+2/5
15/20х+8/20х=21/40-60/40+16/40
23/20х=-23/40
х=-23/40*20/23
х=-1/2
б)5х:20=0,5:12
5х*12=0,5*20
60х=10
х=10:60
х=1/6