Answer:
\(A=3.5\cdot{x}\)
Step-by-step explanation:
Area is defined as width mutiplied by length. We assume the desk is rectangle. The following equation represents the area of the desk:
\(A=3.5\cdot{x}\)
A is the area and x is the length. We can therefore determine the length:
\(x=A/3.5=42/3.5=12\)
The length is 12 ft