Question 302543
area of field ___ 50 * 120 = 6000


area of field and  border ___ 6000 + 1800 = 7800


width of field and border ___ 50 + 2b (border on BOTH sides)


length of field and border ___ 120 + 2b (border on BOTH ends)


(50 + 2b)(120 + 2b) = 7800 ___ 6000 + 340b + 4b^2 = 7800


4b^2 + 340b - 1800 = 0 ___ b^2 + 85b - 450 = 0


factoring ___ (b + 90) (b - 5) = 0


b = 5


b = 90 not realistic