Respuesta:
1) 2/3 - 1/3 = 2 - 1/3= 1/3
2) 4/5 - 2/5 = 4 - 2/5= 2/5
3) 9/10 - 4/10 = 9 - 4/10 = 5/10
4) 9/11 - 7/11 = 9 - 7/11= 2/11