Can someone help me with this ?!! Plz

Acircle has a circumference of 28.36 units what is the diameter of the circle

1c) the number 131 is a term in the sequence defined by the explicit rule f(n)=5n-4. which term in the sequence is 131? 2a) write the first four terms of the function f(n)=n^2-1 2b) what is the 10th term of the sequence defined by the explicit rule f(n)=n^2-1 2c) the number 224 is a term in the sequence defined by the explicit rule f(n)=n^2-1. which term in the sequence is 224?

Pyramid shown has a square base that is 18 inches on each side has a surface area of 164 square inches what is the slant height