Data Sufficiency

Ans would be A

(x+y)^2 = x^2+y^2+2xy ----------(1)

(x-y)^2 = x^2+y^2-2xy ------------(2)

you need to find (1)/(2)

stmt 1 - x^2+y^2 = 3xy

(1) will be 3xy+2xy = 5xy
(2) will be 3xy-2xy = xy

(1)/(2) = 5 SUFF

Stmt 2 - xy= 3. No info to calculate x^2+y^2 so NOT SUFF

Ans A