Final answer:
In Angie's equation for yearly earning E based on sales s, the independent variable is the total sales, represented by 's'.
Step-by-step explanation:
In the equation E=0.03s + 25,000, used to determine annual earnings E based on total sales s, the independent variable is the total sales, represented by s. This is because the independent variable is the value that can be changed or controlled in a situation, which in this case is the total sales amount. The earnings E are dependent on these sales, making s the independent variable and E the dependent variable.