3 & 6 - LCM = 3. 3's multiples are 3, 6, 9,12, 16, etc. 6's multiples are 6, 12, 18, etc. therefore, the least common multiple is 6.
GCF - 3's factors are 1, 3, and 6's factors 1, 2, 3. so the greatest common factor is 3.
7/10 > 3/8
I found this by first finding a common denominator, so for this it will be 40. 10 can go into 40 four times, so you do 7x4 and that is 28, so 7/10 is 28/40.
3/8 is 15/40 because 8 goes into 40 five times, so you do 5x3 which is 15, so the fraction is 15/40. 15/40 is less than 28/40 because 28 > 15
Answer: the answer to lg is 18