first of all your not making the equation clear but i will try and help you.

if u mean simplifying both equations then it is easy.

=> (sin3t) (t+2) = tsin3t+2sin3t

it is a simple cross muntilplication of both brackets

=> sin3t *t = tsin3t

and

=> sin3t * 2 = 2sin3t

Because of the + sign in (t+2), you add the cross multiplication.

therefore u get:

=> tsin3t+2sin3t

I hope this helps you

Greetings