Determine the numerical value of y=(a+1)(b+1), knowing that ab= -6 and a+b=1

Y = (a + 1) (b + 1)
Expand the RHS of the equation

y = ab + a + b + 1
Since ab = - 6 and a+b = 1 by substituting the known values into the expanded equation

y = (ab) + (a + b) + 1
   =  (-6) + (1) + 1
   = - 4