Question 301901
y^2 + 7y - 18 = (y+9)(y-2) 

y^2 + 2y - 63 = (y-7)(y+9)

Therefore, 

(y^2 + 7y - 18) / (y^2 + 2y - 63) = (y+9)(y-2) /(y-7)(y+9)

you can cancel (y+9) from the denominator and numerator 

therefore the solution becomes :

(y-2)/(y-7)