3.24m
the longest piece will be associated with 8 parts of the ratio.
divide 144 by 8 to find 1 part of the ration then multiply this value by 6 and 4 for the remaining parts of the ratio
= 18 cm ← 1 part
6 parts = 6 × 18 = 108 cm
4 parts = 4 × 18 = 72 cm
length = 144 + 108 + 72 = 324 cm = 3.24m