It depends if 24cm is the long dimension or the short one...it's the answer if 24cm is the short dim.
if 24cm is the long dimension then the answer is
24/1.618
The answer could be 11.8L
If rounded 12L
1.
5u - 2u = 3u (diff. between longest and shortest)
3u = 87cm
1u = 87cm ÷ 3 = 29cm
5u + 4u + 2u=11u
11u = 11 x 29cm = 319cm
Ans: 319cm
2.
9u = 1350
1u = 1350 ÷ 9 = 150
6u + 5u = 11u
11u = 11 x 150 = 1650
Ans: 1650
-182=2(1+2x)-2
2*1=2
2*2x=4x
-182=4x+2-2
-182=4x
-45.5=x