What is the value of z in the equation 3z+9=z?

Toyland is having a sale. all items are 20% off. how much will you save on an item that usually sells for 95$ explain your

The base of a triangle exceeds the height by 9 inches. if the area is 180 square inches, find the length of the base and the height of the triangle.

X+ y = 5 ; x - y =3 solve using linear combination