4) simplifique matematicamente as frações numéricas apresentad...

Resolvendo das operacao como indique o enunciado :

4.-)Simplificando as fracoes :

a.-)15/21...(÷3)
=> 5/7

b.-) 140/182...(÷2)
=> 70/91

c.-) 390/234..(÷3)
=> 130/78 ...(÷2)
=> 65/39

5.-) Efetue

a.-) 1/2 + 4/5 + 3
=> 5/10 + 8/10 + 3
=> 13/10 + 3
=> 13/10 + 30/10
=> 43/10

b.-) 17/5 - 7/4 + 3/10
=> 68/20 - 35/20 + 3/10
=> 33/20 + 3/10
=> 33/20 + 6/20
=> 39/20

c.-) 23/6 - 19/12 + 79/18 - 11/3
=> 46/12 -19/12 + 79/18 - 11/3
=> 27/12 + 79/18 - 11/3
=> 81/36 + 158/36 - 11/3
=> 239/36 - 11/3
=> 239/36 - 132/36
=> 107/36

d.-) 4/9 x 18/36 x 5/8
=> 72/324 x 5/8
=> 360/2593..(÷2)
=> 180/1296...(÷2)
=> 90/648...(÷3)
=> 30/216...(÷3)
=> 10/72...(÷2)
=> 5/36

e.-) 9/5 x 12/9 x 5/12
=> 108/45 x 5/12
=> 540/540
=> 1

f.-) 9/5 x 4/7 x 36/13 x 11
=> 36/36 x 36/13 x 11
=> 1296/455 x 11
=> 14256/455

g.-) 11/4 ÷ 9
=> 36/11

h.- ) 9/2 ÷ 7/5
=> 14/35​