2. Sister = 50%

Brother = 10% remainder (50% x 10% = 5%)

5 children = (100% - 50% - 5%) / 5 = 9%

9% = 36 bookmarks => 1% = 4 bookmarks

Total bookmarks she has at first (100%) = 4 x 100 = 400 bookmarks

3. 1st shakes with 2, 3, 4, 5, 6, 7, 8

2nd shakes with 3, 4, 5, 6, 7, 8

3rd shakes with 4, 5, 6, 7, 8

...... 7 shakes with 8

7 + 6 + 5 + 4 + 3 + 2 + 1 = 28 hand shakes

4. T : S => 3 : 8

T : C => 9 : 2

x3 T : S => 9 : 24

C : S => 2 : 24

Therefore, C : S => 1 : 12

5.

P : [40%][40%][20%] [40%][20%]

J : [25%][25%][12.5%] [25%][12.5%]

Let P = x

J = x + 0.6x = 1.6x

x + 1.6x = 130

2.6x = 130

x = 50

P = 50 yrs old now.

P + 20 yrs later = 50 + 20 = 70 yrs