dau coroană ,vă rog ajutați-mă!

1)
a)
x=y |•✓2
✓2x=✓2y |-1
✓2x-1=✓2y-1
b)
x=y |:2
x/2=y/2 |+3
x/2+3=y/2+3
2)
[tex] \sqrt{10} x = \sqrt{14} y | \div \sqrt{2} \\ \sqrt{5}x = \sqrt{7} y | + 2 \\ \sqrt{5} x + 2 = \sqrt{7} y + 2[/tex]
3)
4a=5b |•3
12a=15b
14c=10d |:2
7c=5d
→12a+7c=15b+5d