Respuesta :

1). 2/3 ÷ 3/6

=> 2/3 ÷ 3/6

=> 2/3 × 6/3

=> 2/1 × 2/3

=> 4/3

2). 1/5 + 3/4

=> 1/5 + 3/4

=> 1 × 4/5 × 4 + 3 × 5/4 × 5

=> 4/20 + 15/20

=> 4 + 15/20

=> 19/20

3). 15/3 × 21/5

=> 15/3 × 21/5

=> 15 × 21/3 × 5

=> 315/15

=> 21 × 15/1 × 15

=> 21