①At first :

Jerry has 4u
Tom has 4u + 60 = 4 x (1u + 15)

Tom gave ¼ of his stamps to Jerry. That's 1u + 15.

Now Tom has 3 x (1u + 15)
= (3u + 45) stamps

Now Jerry has 4u + 1u + 15
= (5u + 15) stamps


②Then,

Jerry gave 2/5 of stamps to Tom.

5u + 15 = 5 x (1u + 3)

So Jerry gave 2 x (1u + 3) = 2u + 6 stamps to Tom

Jerry now has 3/5 of his stamps left
= 3 x (1u + 3) stamps
= 3u + 9 stamps

Tom now has 3u + 45 + 2u + 6
= (5u + 51) stamps


③ Tom's uncle gave Tom another 87 stamps.

In the end, Tom has 5u + 51 + 87
= (5u + 138) stamps


Since Tom has twice of his stamps at first,

5u + 138 = 2 x (4u + 60)
5u + 138 = 8u + 120

Rewrite as :

5u + 120 + 18 = 5u + 120 + 3u

This tells us that 3u = 18
1u = 18 ÷ 3 = 6

a) Jerry gave (2u + 6) stamps to Tom

= (2 x 6 + 6) stamps
= (12 + 6) stamps
= 18 stamps

b) Tom had (5u + 138) stamps in the end
= (5 x 6 + 138) stamps
= (30 + 138) stamps
= 168 stamps

Great and clear! Thanks much!

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