Problem: john is building a rectangular fence around a garden . the length will be 5 feet shorter than its width . if the total area of the garden is 176 square feet , what is the length of the diagonal ( in feet ) ? 
Options: ['a ) between 18 and 19', 'b ) between 19 and 20', 'c ) between 20 and 21', 'd ) between 21 and 22', 'e ) between 22 and 23']
b