From the sum of 3x - y + 11 and -y – 11, subtract 3x - y - 11.
The algebraic equation for above problem will be as
[(3x - y + 11)+ (-y - 11)] - ( 3x - y - 11)]
= 3x - y + 11 - y - 11 - 3x + y + 11
= 3x - 3x - y - y + y +11 - 11 + 11
= -y + 11