Answer:
The least common denominator is 21.
Step-by-step explanation:
First, you must find the least common factor of the two:
3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30
7: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70
Second, you must increase the fractions:
[tex]\frac{1}{3}[/tex] × [tex]\frac{7}{7}[/tex] = [tex]\frac{7}{21}[/tex] [tex]\frac{3}{7}[/tex] × [tex]\frac{3}{3}[/tex] = [tex]\frac{9}{21}[/tex]
