hello :
y = x2 + 3x -3.... (1)
2x - 1 = y ..........(2)
subsct in (1) :
2x-1 = x² +3x -3
x² + x -2 = 0
(x+2 )(x-1 ) = 0
x+2=0 or x-1 = 0
x=-2 or x=1
if : x = -2 y = 2(-2)-1 =-2
if : x = 1 y = 2(1)-1 = 1
values of x will (x, y) be a solution of the system : (-2,-2),(1,1)