Răspuns :
0,(6)=6/9=2/3
0,75=75/100=3/4
0,8=8/10=4/5
0,8(3)=83-8/90=75/90=5/6
a=2/3 b=3/4,c=4/5,d=5/6 xd
a+b+c+d=3804
2/3xa=3/4xb =4/5xc+5/6xd=k
2a/3=k =>2a=3k =>a=3k/2
3b/4=k => b=4k/3
4c/5=k=> c=5k/4
5d/6=k =>d=6k/5
3k/2+4k/3+5k/4+6k/5=3.804
aducem la acelasi numitor 60
90k+80k+75k+72k=3804x60
317k =228.240
k=228.240/317
k=720
a=3k/2 =>a=3x720/2 =>a=1080
b=4k/3 b=4x720/3 b=960
c=5k/4 c=5x720/4 c=900
d=6k/5 d=6x720/5 d=864
1080+960+900+864=3804
2)a/1/6=b/1/15=k
6a=15b=>a=15b/6
15/6=2,5
6x250%=15
250% din a=b
0,75=75/100=3/4
0,8=8/10=4/5
0,8(3)=83-8/90=75/90=5/6
a=2/3 b=3/4,c=4/5,d=5/6 xd
a+b+c+d=3804
2/3xa=3/4xb =4/5xc+5/6xd=k
2a/3=k =>2a=3k =>a=3k/2
3b/4=k => b=4k/3
4c/5=k=> c=5k/4
5d/6=k =>d=6k/5
3k/2+4k/3+5k/4+6k/5=3.804
aducem la acelasi numitor 60
90k+80k+75k+72k=3804x60
317k =228.240
k=228.240/317
k=720
a=3k/2 =>a=3x720/2 =>a=1080
b=4k/3 b=4x720/3 b=960
c=5k/4 c=5x720/4 c=900
d=6k/5 d=6x720/5 d=864
1080+960+900+864=3804
2)a/1/6=b/1/15=k
6a=15b=>a=15b/6
15/6=2,5
6x250%=15
250% din a=b