What is the solution to this problem?

In 2015, Nina contributes 8 percent of her $187,000 annual salary to her 401(k) account. She expects to earn a 7 percent before-tax rate of return. Assuming she leaves this (and any employer contributions) in the account until she retires in 30 years, what is Ninas after-tax accumulation from her 2015 contributions to her 401(k) account? (Round intermediate calculations to the nearest whole dollar amount. Round "Future value factor" to 4 decimal places.)

a.	Assume Ninas marginal tax rate at retirement is 30 percent.

b. Assume Ninas marginal tax rate at retirement is 20 percent.

c. Assume Ninas marginal tax rate at retirement is 40 percent.