3{[3(x-5)15]-[3(4x-3) +3]}

I need help to simply this. I have been working on this for 2 hours and still don’t get it, can anyone help?

It seems as if you have omitted a + or - sign in front of the 15. I will assume a +.

3{[3(x-5)+15]-[3(4x-3) +3]} =

3{(3x - 15 + 15) - (12x - 9 + 3) =

3(3x - 12x + 6) =

3(-9x + 6) = -27x + 18