Zion is finding the difference between of the polynomial expressions ( 1/6 x²- 1/3 x) and (- 5/18 x²+ 1/6 x- 17/18 ) Zion sets up the expression, ( 1/6 x²- 1/3 x)-(- 5/15 x²+ 1/6 x- 17/15 ) Is this expression set up correctly?