Respuesta :

TSO
[tex]89 - 39 = (80 +9) - (30+9) = 80 - 30 + 9 - 9 = 80 - 30 = \boxed{50}[/tex]
Leader
89 - 39 = 50

The 9s in the ones digit 9 - 9 = 0
8 - 3 = 5

So 50
RELAXING NOICE
Relax