Answer:
The length of the mural was 90 inches
Explanation:
The scale is the relationship that exists between the magnitudes of a drawing and the actual dimensions. This is:

scale factor = Drawing length /Actual length
In this case, you have that:
- scale factor= 0.2
- drawing length= 18 inches
So:

Solving this, you get:

actual length=90 inches
So, the length of the mural was 90 inches