You need at least one more fraction in order to have a common denominator.
The common denominator is 28.
There is none because the Least Common Denominator (or LCD) is the Least Common Multiple (LCM) of the denominators of a pair of fractions.
100
924
the common denominator for 9/8 and 7/20 is 40. (45/40 and 14/40)
A common denominator, though not the least one, is 200.
350
56
The common denominator is 28.
A common denominator, though not the least, is 168.
A common denominator, though not the least one, is 14*49 = 686.
A common denominator, though not the least one, is 14*12 = 168.
There is none because the Least Common Denominator (or LCD) is the Least Common Multiple (LCM) of the denominators of a pair of fractions.
The least common denominator is 70.
There is none because the Least Common Denominator (or LCD) is the Least Common Multiple (LCM) of the denominators of two or more fractions.
7.
Their product.