To find the LCM you must find all factors of the numbers, and then multiply all the factors together including the ones that are not shared among the numbers.
For example,
Factors of 10: 2×5
Factors of 30: 2×3×5
LCM of 10 and 30: 2×3×5 = 30
However do note not to multiply a factor more than once if it is shared among two numbers.
The fraction of 81/41 is the best simpilfied you can do. Other ways you can simplify it as decimal : 1.97560 with a line over it as it will repeat or as a mixed number form : 1 and 40/41