X=2Y+5

Substitute X=2Y+5 into ② to get.

5(2Y+5)-3Y= 1/2

10Y+25-3Y= 1/2

7Y=-49/2

Y=-7/2

X=2Y+5=-7+5=-2

∴X=-2 Y=-7/2

Second, because 2x-y-3 = 0 (1)

So 4X-2Y-6=0 ③.

Add ②+③ and you will get

7X- 14=0 X=2

Substitute X=2 into ①, and you get

4-Y-3=0 Y= 1

∴X=2 Y= 1