Answer:
The marginal tax rate for the additional $6000 is 15.58%.
Step-by-step explanation:
Arlene has a taxable income of $34,000.
Her tax liability is currently $4636.
Her income is to be increased by $6000.
Her tax liability will increase to $5571.
Marginal tax rate
=

=

=

= 0.1558
So the marginal tax rate is 15.58%.