Answer:
x + 31[tex]\frac{1}{2}[/tex]
Step-by-step explanation:
P = x + 2/(21 - 2x) + x + 2/(21 - 2x) + x + 2/(21 - 2x) + x
= x + 21/2 - x + x + 21/2 - x + x + 21/2 - x + x
= x + 21/2 + 21/2 + 21/2
=x + 31[tex]\frac{1}{2}[/tex]
