A culture started with 5000 bacteria after four hours it grow to 5500 bacteria predict how many bacteria will be presented after 13 hours round your answer to the nearest whole number

Afarmer has a large field that is x feet in length. he wants to fence in a rectangular section in the middle of the field , leaving a length of 100 feet of open field behind each end of the fenced rectangle.he also wants the width of the fenced-in space to be 100 feet less than its length. find the expressions to represent the length and width of the fenced section of the field