Answer:
X = 3 , Y = 1
Explanation:
Given equations are 
Y = X - 2 ........ A
Y = -2X + 7 .....B 
Put the value of Y from eq A to the eq B 
∴  X - 2 = -2X + 7
Or, X + 2X = 7 + 2
Or, 3X = 9 
Or, X = 

∴ X = 3
Now to get the value of Y , put X value in any of above two Eq.
pu X value in Eq A
We get Y = X - 2
so, Y = 3-2 
Y= 1
Hence X = 3 and Y = 1 Answer