Stefan sells Jin a bicycle for ​$ and a helmet for ​$. The total cost for Jin is ​% of what Stefan spent originally to buy the bike and helmet. How much did Stefan spend​ originally? How much money did he make by selling the bicycle and helmet to​ Jin?

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