The complex solutions come in pairs and the only difference between them is the sign between the real and imaginary part, so one of the other two solutions is

. The third solution can be easily found using the rational root theorem, and it's equal to -1.
Rational: (-15.333), (sqt of 400), (8.62134), (15 5/6), (-3 4/5)
Irrational: (sqt of 6), (pi), (sqt of 56), (sqt of 31)
The yellow yarn was 160 inches longer than the blue yarn.
https://www.cpsb.org/site/handlers/filedownload.ashx?moduleinstanceid=8283&dataid=7357&FileName=4.HW.17.pdf