Which relation is a function?

a coordinate grid containing a u shaped graph with arrows on its ends. the u shape opens upwards and the bottom of the u shape is located at the origin.

coordinate grid with graph of a vertical line at x equals 3.

a coordinate grid containing a u shape with arrows on both ends that opens to the right. the bottom portion of the u passes through the origin.

a coordinate grid with the graph of a circle centered at the origin and passing through the point begin ordered pair 2 comma 1 end ordered pair.

Francisco's credit card has an apr of 28.98%, calculated on the previous monthly balance. his credit card record for the last 7 months is shown in the table below francisco is trying to figure out what this all means. answer the following questions: what is the total amount that francisco has paid in interest over the 7 months? what is the total amount that francisco has made in payments over the 7 months? how much of francisco's payments have gone to paying down the principal on his account? what is francisco's new balance at the end of month 8? what will francisco be charged for interest for month 8?