Answer:
According to Exhibit 8-8, the phase-out threshold for married filing jointly is $400,000.
For Trey's first situation where his AGI is $103,300, he will be able to claim the full child tax credit of $3,000 for his two daughters.
For Trey's second situation where his AGI is $431,000, he will not be able to claim any child tax credit for his two daughters as his AGI exceeds the phase-out threshold.
For Trey's third situation where his AGI is $421,200 and his daughters are ages 10 and 12, he will be able to claim the full child tax credit of $6,000 for his two daughters.
I hope this helps you! Let me know if you have any other questions.