Answer:
14
Step-by-step explanation:
We are given with two [tex]5\ digit[/tex] numbers whose first [tex]3 \ digits[/tex] are same.
It is given that their sum is [tex]123422[/tex]
adding the last two corresponding digits gives,
[tex]0+2=2\\1+1=2[/tex]
Now adding the rest,
[tex]C+C \ should\ be\ 14[/tex] to get [tex]4[/tex]
[tex]1 \ carries\\B+B[/tex] should not give anything to carry as that will make A in decimal to satisfy the addition.
Therefore,
[tex]B+B \ has \ to \ be 1+1=2,+ 1 \ carry=3[/tex]
Thus [tex]B= 1[/tex]
And finally,
[tex]A+A=12\\A=6[/tex]
Thus [tex]A=6, B=1 \ and \ C=7[/tex]
Now simplifying
[tex]A+B+C\\=6+1+7\\=14[/tex]
Thus [tex]14[/tex] is the answer.