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 would be 50
The LCD of 7/10 and 18/25 is 50.
25
A common denominator, though not the least, is 1700.
A common denominator, though not the least, is 1700.
A common denominator, though not the least, is 150.
It is 100
225
the answer is five
650
1200
100