Well, you don't usually multiply fractions with common denominators, you just multiply across then simplify if you can.
Ex.
5/6 X 4/5= 20/30= 2/3
say its 3/4 x 5/6, you would times together the two bottom numbers so it would be 4x6=24, you then multiply diagonaly so 3x6=18 and 4x5=20. you then have 18+20/24 = 38/24 = 1 14/24 and you can then cancel it down. I hope thats easy to understand. / means over so 3 over 4 ect
