3/5+x=4/5

y-2/7=6/7

11/25-k=7/25

d+2/9=1/9+7/9

3/5+x=4/5
x=4/5-3/5
x=1/5

y-2/7=6/7
y=6/7+2/7
y=8/7=1 1/7

11/25-k=7/25
-k=7/25-11/25
-k=-4/25
k=4/25

d+2/9=1/9+7/9
d=1/9+7/9-2/9
d=6/9
d=2/3