In 2019, Elaine paid $2,640 of tuition and $920 for books for her dependent son to attend State University this past fall as a freshman. Elaine files a joint return with her husband. What is the maximum American opportunity tax credit that Elaine can claim for the tuition payment and books in each of the following alternative situations? (Leave no answer blank. Enter zero if applicable.)

a. Elaines AGI is $83,000.

b. His AGI is $423,600.

c. His AGI is $427,700, and his daughters are ages 10 and 12.