Final answer:
To divide expressions with negative exponents, subtract the exponents and divide the coefficients. In this case, the simplified expression is -3v^(-12).
Step-by-step explanation:
To divide expressions with negative exponents, you need to follow the rule that states you subtract the exponents and divide the coefficients. In the given expression, 21v^(-6) ÷ (-7v^(-6)), the coefficient 21 is divided by -7 to get -3. Then, the exponents -6 are subtracted to get -12. So the simplified expression is -3v^(-12).