PLEASE HELP! I DONT HAVE LONG

The late fee for library books is $2.00 plus 15¢ each day for a book that is late. if maria’s fee for a late book was $3.20, write and solve a linear equation to find how many days late the book was.

What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

Consider circle c with angle acb measuring 3/4 radians.if minor arc ab measures 9 inches, what is the length of the radius of circle c? if necessary, round your answer to the nearest inch.