Answer:Decay
Step-by-step explanation: because of perenthesis
We're going to solve each of the systems to determine the solution.
<u>System
</u>

using a graph tool
the solution is the line 
see the attached figure N 
<u>System
</u>

using a graph tool
the solution is the shaded area
see the attached figure N 
<u>System
</u>

using a graph tool
The system has no solution
see the attached figure N 
<u>System
</u>

using a graph tool
the solution is the shaded area
see the attached figure N 
therefore
<u>the answer is</u>
<u>System
</u>

0.7/1 of a wall per person