Calculate the amount of the child and dependent care credit allowed for 2018 in each of the following cases, assuming the taxpayers had no income other than the stated amounts

a. William and Carla file a joint tax return. Carla earned $26,000 during the year, while William attended law school full-time for 10 months and earned no income. They paid $3,500 for the care of their 3-year-old child, Carl.  

b. Raymond and Michele file a joint tax return. Raymond earned $32,500 during the year, while Michele earned $8,000 for the year from a part-time job. They paid $7,000 for the care of their two children under age 13. 

c. Beth is a single taxpayer who has two dependent children under age 5. Beth earned $23,500 in wages during the year and paid $6,700 for the care of her children.