40 is the Least Common Denominator of 3/10 and 7/8, since it is the Least Common Multiple of 8 and 10. LCDs are usually used to add two fractions, and if that is what you are trying to do, 3/10 + 7/8 = 12/40 + 35/40 = 47 / 40 = 1 7/40.
10
20
20
3
The LCD of 7/10 and 18/25 is 50.
LCD(7, 5, 10) = 10
56
If that's 3/8 and 7/10, the LCD is 40.If not, it's 13490
The LCD for 4/7 and 3/5 is 35.
The LCD for 3/4 and 4/7 is 28.
60
7 over 10 is greater. If you put both of these numbers in decimal you will get 7 over 10 as .7 and 3 over 10 as .3 The number 7 is greater than 3 so 7 over 10 is greater than 3 over 10.