Repayment Schedule question!?

1)The repayment schedule is for a $1,300 loan at 7.5% for 6 months. What is the amount for interest at payment 4? 2)The repayment schedule is for a $1,300 loan at 7.5% for 6 months. What is the principal after the first payment? Graph belongs to both... show more 1)The repayment schedule is for a $1,300 loan at 7.5% for 6 months. What is the amount for interest at payment 4?

2)The repayment schedule is for a $1,300 loan at 7.5% for 6 months. What is the principal after the first payment?

Graph belongs to both questions:
http://fc07.deviantart.net/fs71/f/2013/1...

I need help solving this. I tried various was to solve this and I still don't get the correct answer.

Formulas:

Interest= Principal*Rate*Time

Payment to Principal= Monthly Payment-Interest

New Principal= Previous Principal -Payment to Principal
1 answer 1