Answer:
The answer is B. x^4/21
Step-by-step explanation:
Remeber when you are multiply exponents you have to add them
[tex]\frac{-2}{3} +\frac{6}{7}[/tex]=[tex]\frac{4}{21}[/tex]
Exponents RULE [tex]a^{b}*a^{c}=a^{b+c}[/tex]
