Use the line tool to graph the equation on the coordinate plane

How is working backward similar to solving an equation?

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document

Point s lies between points r and t on . if rt is 10 centimeters long, what is st? 2 centimeters 4 centimeters 6 centimeters 8 centimeters