How do you calculate 3x-9y?

3(x-3y)

Step-by-step explanation: first you have to take the 3x and split it up so it can make 3(x-3y) then you have to rewrite it to -9 as 3x3 and then factor out common term 3 which would be your final answer 3(x-3y)

b) k’(6, 4); l’(3, 3)

step-by-step explanation:

a 270° clockwise rotation maps every point (x, y) to (y, -x). (it negates the x-coordinate and then switches it and the y-coordinate.)

this means the endpoints of the side congruent to kl, k' and l', would be mapped as:

k'(-4, 6)→(6, 4)

l'(-3, 3)→(3, 3)