Respuesta :

apologiabiology
use distributive prpoerty
a(b+c)=ab+ac

distribute each
3k(-5k+21)=-15k^2+63k

2(2.5k+90)=5k+180

so nowe we have
-15k^2+63k+5k+180
add like terms
-15k^2+68k+180
that is the answer