heres a start
ab = cd
a + b + c +d = -b/a = 11/6
abc + abd + acd + bcd = -d/a = -22/6 = -11/3
subbing ab = cd,
abc + abd + a(ab) + b(ab) = -11/3
ab(a + b + c + d) = -11/3
ab (11/6) = -11/3
ab = -2
or
abcd = e/a = 24/6 = 4
ab(ab) = 4
(ab)2 = 4
ab = +-2 (now thats just plain weird =S)...