Resposta:

a)840

b)4

Explicação passo a passo:

a)

20,70,120| 2

10,35,60|2

5,35,30|2

5,35,15|3

5,35,5|5

1, 7, 1|7

1,1,1

2³.3¹.5¹.7¹=840

b)

200,300,440|2*

100,150,220|2*

50,75,11|2

25,75,11|3

25,25,11|5

5,5,11|5

1,1,11|11

1,1,1

2²=4