Answer :
Multiply 3 to everything inside the bracket, then collect like terms and simplify.
= 20 - 15w - 6 - 4w
= 20 - 6 - 15w - 4w
= 14 - 19w
= 20 - 15w - 6 - 4w
= 20 - 6 - 15w - 4w
= 14 - 19w