What is the value of z?

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

Which rule describes the composition of transformations that maps ajkl to aj"k"l"? ro. 900 o to, -2(x, y) to, -20 ro, 900(x, y) ro, 9000 t-2. o(x,y) t-2, 00 ro, 900(x, y)

The volume of a box varies directly with its length if a box in the group has a length of 30inches and k=24 what is its volume