nikitaxt36 7/4-y=27/10
-y=27/10-7/4
-y=54/20-35/20
-y=19/20
y=-19/20

irina00101 1 3/4 - у = 2 7/10
-у=2  7/10--1 3/4
-у=1  21/40--30/40
-y=54/20-35/20
-y=19/20
y=-19/20