Answer:
84+n=342
Step-by-step explanation:
you would subtract 84 from 342 to find the width since it is perimeter.
With digits 8, 5, and 6, an odd number must end in 5.
So far, we have _ _ 5.
The 8 is in the hundreds place.
Now we have 8_5.
The only place left for the 6 is the tens place.
The number is 865.

Explanation:
Area is pi×r^2 and you times it by the fraction of the circle you have as its not a full circle.
It is C. Associative property of multiplication