Respuesta :
use the keep,change,change method.
19 + 11
19,keep, "-" change to addition, -11,change to positive
now use this
19 + 11 = (30 )
use the keep,change,change method.
19 + 11
19,keep, "-" change to addition, -11,change to positive
now use this
19 + 11 = (30 )