need help with three case scenarios using rate function to calculate interest payments

[MysJee]

I need help for this scenario

I have gotten the first scenario but can't seem to get the next two, Questions: In this third scenario, I only make a down payment of $20,000 and i'm forced to make payments of $8,000 a month over 4 years. I need to use the Rate function in cell I10 to figure out how much my interest payments are and then fill in the supporting data in cells I4, I13 and I14. The document is on the 2nd sheet in the attachment named Goal seek.