In a survey of students , every student studies at least one of the three subjects Maths English and Science . The number of students who study only one subject is twice the number of students who study only two students . If 20 students study all three and 80 students who study only two subjects, find the total number of students in the survey. ​

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