Question 165788
Let I be the amount Ivan wants.
Denys wants {{{D = 2I}}}
Zoe wants {{{Z = 2D = 2*(2I) = 4I}}}
Zoe also wants {{{Z= E/2}}} so {{{4I = E/2}}} and {{{8I = E}}}

Added up, they use the whole pickle
{{{30 = I + Z + D + E}}}
{{{30 = I + 4I + 2I + 8I}}}
{{{30 = 15I}}}
{{{2 = I}}}
If Ivan gets 2, then Denys gets 2*2 = 4
Zoe wants 4*I = 4*2 = 8
Ethan gets 8I (Ethan is a big pickle eater) - so E get 8*2 = 16