Alright so..
For a) it should be the second choice. You can clearly see as months pile on, so does the money. Now they ask for the rate. Let’s do the 6 months one. 423/6 is 70.5.
So the rate is for every 1 month, it’s $70.50 added. And if I’m not wrong, I believe she started with $70.50 in the bank. She rich rich