I need to understand, in full, how to work out the b section of this problem. It took me a while to understand how to get the a. section especially...

I need to understand, in full, how to work out the b section of this problem. It took me a while to understand how to get the a. section especially understanding how to determine the payment formula: i.e.: payment = FV / (((1 + rate)^time - 1)/rate). Please explain all steps.