Let Jerry's stamps at first be 4 units.
So Tom's stamps at first = 4 units + 60

① Tom gave ¼ of his stamps to Jerry
→ ¼ of (4 units + 60)
= 1 unit + 15

Number of stamps Tom has now
= 4 units + 60 - 1 unit - 15
= 3 units + 45

So number of stamps Jerry has now
= 4 units + 1 unit + 15
= 5 units + 15



② Jerry gave 2/5 of his stamps to Tom
→ 2/5 of (5 units + 15)
= 2 units + 6

Tom now has :
3 units + 45 + 2 units + 6
= 5 units + 51


③ Then, Tom's uncle gave him 87 stamps.

Tom now has :
5 units + 51 + 87
= 5 units + 138


In the end, Tom had twice the number of stamps he had at first.


5 units + 138 = 2 × (4 units + 60)

5 units + 138 = 8 units + 120

→ 3 units = 18
1 unit = 6

So for part (a) :

number of stamps Jerry gave to Tom
= 2 units + 6
= 2 x 6 + 6
= 12 + 6
= 18



part (b) :

Number of stamps Tom had in the end

= 8 units + 120
= 8 × 6 + 120
= 48 + 120
= 168

OR

Number of stamps Tom had in the end

= 5 units + 138
= 5 × 6 + 138
= 30 + 138
= 168

at first → T:J:T+J = u:u-20: 2u-60
in the end → T+J = 2u-87+J

internal transfer total unchanged
2u-60 = 2u-87+J → J = 27 (in the end)

b4 J give ⅖ to T【aft ¼ given by T】
J → 27÷ ⅗ = 45

45+T = 2u-60
T = 2u-105 = ¾u ⇨ u = 84【T at first】

(b) 2u = 168 (Ans)

(a) ⅖ × (84-60 + ¼ ×84) = 18 (Ans)