Sandy is working as a waitress and wants to average over $90 a night in tips. She works 4 days a week. So
far, she has made $95, $87, and $88 this week. How
much must she make on her last day of work to meet
her goal?

solve systems of equations by graphing. a system of linear equations contains two or more equations e.g. y=0.5x+2 and y=x-2. the solution of such a system is the ordered pair that is a solution to both equations. to solve a system of linear equations graphically we graph both equations in the same coordinate system

inverse operation of addition

the solution, from the graphing of the two lines, is (3,2), i.e., x = 3, y = 2.