1.
3х-2у =1/2
4у-х=2/3, x=4y-2/3
3*(4y-2/3)-2y=1/2
12y-2-2y=1/2
10y-2=1/2
10y=2 1/2
y=1/4
x=4*1/4-2/3=-1/3
2.
2х-3у=-1
у/х=0,75 , y=0.75x
2x-3*0.75x=-1
2x-2.25x=-1
-0.25x=-1x
x=4
y=0.75*4=3
3. (1/2+0,125-1/6)*(6,4:80/3)+1/8
1) 1/2+0.125=1/2+1/8=4/8+1/8=5/8
2) 5/8-1/6=15/24-4/24=11/24
3) 6.4:80/3=6 2/5 : 80/3 = 32/5 : 80/3 = 6/25
4) 11/24*6/25=66/600=11/100
5) 11/100+1/8=44/400+50/400=94/400=47/200