You only need the denominators to find the common denominator. Since 41, 97 and 6 have no factors in common the lowest common denominator is the product 41*97*6=23862. All the fractions can be expressed as multiples of 1/23862. 3/41=3*97*6/23862, 40/97=40*41*6/23862, 1/6=41*97/23862: 1746/23862, 9840/23862, 3977/23862.