Joan puts $400 into a bank account. each year the account earns 7% simple interest. how much interest will be earned in four years ?

$60
$72
$84
$112

Barney & noblet customers can choose to purchase a membership for $25 per year members receive 10% off all store purchases 1. how much would a member pay per year if he bought $50 worth of items each year? 2. write a slope-intercept equation that expresses how much a member pays per year using x to represent his purchases per year 3. how much would a member have to spend per year to pay off his membership fee?