A student has a savings account earning 9% simple interest. She must pay $1500 for first-
semester tuition by September 1 and $1500 for second-semester tuition by January 1. How much
must she earn in the summer (by September 1) in order to pay the first-semester bill on time and
still have the remainder of her summer earnings grow to $1500 between September 1 and
January 1?