Respuesta :

Answer:  "10" .
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1/2 = x/20 

(1*10) = (2*10) = 10/20 .

Note: 2*10 = 20.

1/2 = 10/20 .

10/20 = ?  ;  Cancel out the zeros to get:  "1/2" ;    "10/20 = 1/2" .