Answer:
C. Distributive property
Step-by-step explanation:
Distributive property says that
[tex]a\cdot (b+c)=a\cdot b+a\cdot c[/tex]
Consider left part of the expression
[tex]\dfrac{6x+9}{3}=\dfrac{1}{3}\cdot (6x+9)[/tex]
By distibutive property,
[tex]\dfrac{1}{3}\cdot (6x+9)\\ \\=\dfrac{1}{3}\cdot 6x+\dfrac{1}{3}\cdot 9\\ \\=2x+3[/tex]
