Rob and Julie, both in their 30s, file a joint income tax return for 2018. Rob's wages are $25,000 and Julie's wages are $33,000 for the year. Their total adjusted gross income is $58,000, and Julie is covered by a qualified pension plan at work but Rob is not.

a.	What is the maximum amount that Rob and Julie may each contribute to their Roth IRAs?
b.	If Julie's wages are $110,000 for 2018, instead of $33,000, and their adjusted gross income is $135,000, (1) what is the maximum amount that Rob and Julie may each deduct for contributions to their traditional individual retirement accounts, and (2) what is the maximum amount they could each contribute to Roth IRAs instead?