Respuesta :

Mathmaster11
You add 5 and 7 then you add 1 and 3
15+37
   ∨   ∨
    5+7=12
15+37
 ∨    ∨
  1+3= 4   
Then add 4 with 12.  4+12=16. I don't know if this works or not but I tried. :)

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