315.
Least common denominator of 7 and 5 is 35.
The Least Common Denominator of 5, 7, and 35 is 1.
The least common denominator is 280.
The least common denominator (LCD) is 630.
35
The least common denominator of 2, 5 and 7 is 70. Since all those numbers are prime, the answer is their product.
140
105
The least common denominator is 28.
It is 630
420
280