Question 255430
Let B = Bill, D = Dave, and J  = JIm.
(i) {{{D = 3J}}}
(ii) J = (1/2)B
(iii) {{{(B + D + J)/3 = 64}}}
From (ii) 
(iv) B = 2J.
Subbing (i), (ii) and (iv) into (iii), we get
(v) {{{2J + 3J + J = 192}}}
(vi) {{{6J = 192}}}
(vii) {{{J = 32}}}
This means that B = 64 and D = 96.
Jim = 32.