Mark is increasing his exercise routine by running and walking at least 4 miles each day. His goal is to burn a minimum of 1,500 calories from this exercise. Walking burns 270 calories/mile and running burns 650 calories/mile. Let w represent the number of miles Mark walks and let r represent the number of miles Mark runs. Write a system of inequalities to model this situation.

w + r 》 4 (greater than/equal to 4)

270w + 650r 》 1500

answer: domain and range mean all possible values of x and y that could be substituted to the inequality. a solution means all possible values that make the inequality statement true. so while the range is still all real numbers, the solution is the shaded area, for which y will always be greater than the line of the function.