Robin files as head of household and has three children who reside in her home all year. her children are ages 12, 15 and 16. robin and all the children are u. s. citizens. robin provided more than half of all her children’s support and she will claim all the children on her federal income tax return. robin’s modified agi is $85,700 and her tax is $15,748. how much child tax credit is robin allowed in 2017?