Answer:
-3(9x-7)
Explanation:
first multiply
20x2=40
and now its -40x+13x+21
then add same variables
-40x+13x=-27x
now its -27x+21
then rewrite the equation
3 x 7=21
-3 x 9x = 27x
now its (-3 x 9x) + (3 x 7)
then the multiply thingy and you got the answer