How do you solve this 8x+y=-16 , -3x+y=-5 using elimination

Steve wants to develop a way to find the total cost of any item including sales tax. the sales tax in his city is 6%. his friend jenna writes the expression x + 6x where x is the cost of the item. explain whether her expression is correct based on the situation.

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.

At your job you're paid $50 per week plus $3 per sale at least how many saled do you need to make in order to have over $250