Problem: the area of a rectangular field is equal to 300 square meters . its perimeter is equal to 70 meters . find the length and width of this rectangle . 
Options: ['a ) w = 15 and l = 20', 'b ) w = 25 and l = 30', 'c ) w = 35 and l = 40', 'd ) w = 45 and l = 50', 'e ) w = 55 and l = 60']
a