when you divide 6/13 by 6/12 you should be getting 12/13
step by step :
take the reciprocal ( flipping the numerator and denominator ) of the second fraction and changing the division sign to multiplication :
6/13 × 12/6
the next step is to multiply the numerator and denominator
6 × 12 / 13 × 6 = 72/78
the fraction can be reduced by dividing numerator and denominator by greatest common factor of 72 and 78
here the greatest common factor will be 6
72 ÷ 6 / 78 ÷ 6
you should get 12 / 13 as an answer
so that's it :)
hope this helped !