According to Mulliken's Scale:
Electronegativity=x=I.E+E.A2=17.42+3.4122=10.416
Thus, the value of x is 10.416.
According to Pauling's Scale:
Electronegativity=y=I.E.+E.A.2×2.8=17.42+3.4125.6=3.72
Thus, value of y is 3.72
∴ x+y0.4=10.416+3.720.4=35.34