Umm, no given amount involved?

Let S = total amount of the shares that Mike, Joe and Susan have equally divided among them

So the three have S/3 each.

Mike:

80% of S/3 to his 4 kids equally, and 20% of S/3 to him.

Joe:

3/4 of S/3 to his 7 kids equally

Susan:

1/2 of S/3 to her eldest, then 1/2 of S/3 to her 3 other kids equally.

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a) how much mike owns

Initially? S/3.

After he gave some to his 4 kids?

20%(S/3)

= 0.20(S/3)

Since 0.20 = 1/5,

= (1/5)(S/3)

= S/15

= (1/5)S

b) how much mikes kids obtain

In total? 80%(S/3) = 0.80(S/3) = (4/5)(S/3) = (4/15)S

Each one? (4/15)S / 4 = (1/15)S each.

C) how much each of joes children obtain

(3/4)(S/3) / 7

= (3S/12) / 7

= (S/4) / 7

= (S/4) * 1/7

= S*1 / 4*7

= S/28

= (1/28)S each.

d) how much sean obtains

Sean who?

Susan? (1/3)S.

Susan's eldest? (1/2)(S/3) = S/6 = (1/6)S.

E) how much each of susans other kids get

(1/2)(S/3) / 3

= (S/6) /3

= (S/6) *(1/3)

= S/18

= (1/18)S each.