the area of a rectangular field is equal to 800 square meters . its perimeter is equal to 120 meters . find the width of this rectangle .
"l * w = 800 : area , l is the length and w is the width . 2 l + 2 w = 120 : perimeter l = 60 - w : solve for l ( 60 - w ) * w = 800 : substitute in the area equation w = 20 and l = 40 correct answer d"
divide(subtract(divide(120, const_2), sqrt(subtract(multiply(divide(120, const_2), divide(120, const_2)), multiply(const_4, 800)))), const_2)