a+2b=6 From the above equation, we can say that maximum value b can take is 3 and minimum value b can take is 0 . a+b+b=6 a+b=6−b a+b is maximum when b is minimum, i.e. b=0 Maximum value of a+b=6−0=6 a+b is minimum when b is maximum, i.e. b=3 Minimum value of a+b=6−3=3 Average =