LCM of 8 and 12 = 24
In every 2.4 m —
top part of wall had: 3 x 3 = 9 (sun sign) and 2 x 3 = 6 (music sign)
bottom part of wall had : 6 x 2 = 12 (sun sign) and 3 x 2 = 6 (music sign)

9 + 12 – 6 – 6 = 9 (more sun sign in every 2.4 m)
108/9 = 12
12 x 2.4 = 28.8

Ans : 28.8 m.

This is a Quantity Each product question.

LCM

0.8 = 4/5 = 12/15

1.2 = 6/5 = 12/10

Figure 1 : figure 2 = 15 : 10 = 3 : 2 

Each means more Sun than Music.

9u = 108

1u = 108 ÷ 9 = 12

2u = 12 × 2 = 24 pieces

24 x 1.2 m = 28.8 m