Explicação passo a passo:

A)

4, 5 | 2

2, 5 | 2

1, 5 | 5

1, 1 | 1

MMC = 2 . 2 . 5 = 20

B)

6, 12 | 2

3, 6 | 2

3, 3 | 3

1, 1 | 1

MMC = 2 . 2 . 3 = 12

C)

10, 15 | 2

5, 15 | 3

5, 5 | 5

1, 1 | 1

MMC = 2 . 3 . 5 = 30

D)

2, 3, 8 | 2

1, 3, 4 | 2

1, 3, 2 | 2

1, 3, 1 | 3

1, 1, 1 | 1

MMC = 2 . 2 . 2 . 3 = 24

E)

5, 6, 10 | 2

5, 3, 5 | 3

5, 1, 5 | 5

1, 1, 1 | 1

MMC = 2 . 3 . 5 = 30