Tom Company offers Jane Company discount terms of $\frac{5}{15},\frac{n}{45}.$ What does this mean?

Jane Company will receive a $5\%$ discount if payment is made within $45$ days.

Jane Company will receive a $15\%$ discount if payment is made within $5$ days.

Jane Company must pay the full amount if payment is made before day $15.$

Jane Company must pay the full amount if payment is made after day $15.$