Evaluate the following using identity ( part 2 ) 4. (0.4a + 1/4 b) (0.4a - 1/4b)
5. (x + 1/y) ( x-1/y)
6. (2/3x + 3/11y) (2/3x - 3/11y)

refer the attachment pls

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18

6mm^3 or .6cm^3

      216

      /   \

  36     6

  /   \     /

6     6   6

factor trees are nice.