??????????

Assume the base of the number is $x$.

Therefore, $=> (4)x+(2)x=(11)x$ $=> 4x^0+2x^0=1x^1+1x^0$ $=> 4+2=x+1$ $=> 6=x+1$ $=> x=6-1$ $=>x=5$

Hence base should be 5 for the given expression.

Let the base be x

= $(4)_{x} + (2)_{x} = (11)_{x}$

= $4 + 2 = x + 1$

= $x = 6-1 = 5$

Correct answer: 5