#10
медведи-1-(2/5+(1-2/5)*2/5=1-(2/5+2/5-4/25)=1-(10/25+10/25-4/25)=1-16/25=9/25=0,36
0,36-x
1-100%
0,36*100=x
-x=-36:(-1)
x=36(%)
#11
8(x/1 7/9-1 3/4)=13
8x/1 7/9-14=13/1
8x=(1 7/9-14)*13
8x=16/9*13-182
8x=16-182
8x=-166:8
x=-2,75
#13
2/7c+9/14c+x=c
6 2/9*2/7+6 2/9*9/14+x=6 2/9
16/9+4+x=6 2/9
x=6 2/9-4-1 7/9
x=2 2/9-1 7/9=1 11/9-1 7/9=4/9