Chapter 1 - Section 1.4 - Solving Linear Equations - Exercise Set - Page 51: 57

$-7$

First, solving for x, $3(x+3)=5(2x+6)$ $3x+9=10x+30$ $7x=-21$ $So,\,\,\,x=-3$ Second, solving for y, $-2y-10=5y+18$ $7y=-28$ $So,\,\,\,y=-4$ Now, inserting values of x and y, $x^{2}-(xy-y)=(-3)^{2}-((-3)(-4)-(-4))=9-(12+4)=-7$