This question wants you to reverse the operations that occurred.
Start with 12 stamps.
Divide this number by 3/4. This represents Carla giving 1/4 of the stamps to Thomas.
[tex]12 / \frac{3}{4} = 16[/tex]
Multiply this number by 2. This represents Jim giving half of the stamps to Carla.
[tex]16 * 2 = 32[/tex]
Multiply this number by 2. This represents John giving half of his stamps to Jim.
[tex]32 * 2 = 64[/tex]
John started out with 64 stamps.