What is the LCD of 1/10 and 1/11?
The least common denominator is 110.
Start with listing your multiples of 11 until you find one that 10 will factor into.
As you continue you will find that the only number that both 11 and 10 go into is 110.
From there you place 110 into the denominator on both fractions. Remember what you do to the bottom you must do to the top.
Then you add them together.