Each week, Eric collects d daisies, of which he gives s to his sister and keeps the rest for himself.Which of the following expressions represents the total number of daisies that Eric keeps for himself over the course of w weeks?

When working through the questions in the no-calculator section of the SAT Math test, you will answer questions on:

Basic math, including fractions, decimals, percentages, and ratios 
Algebra, including linear equations, coordinate geometry, and quadratic equations 
Geometry, which covers both basic shapes and three-dimensional solids
Word problems, including rate of travel, averages, probability, and equation setup 
Tables and graphs, including data analysis