Question

I need help with making plural of thise sentences:

1.Una muchacha guapa-
* know that that I am not using los/las and I need tu change muchacha to muchachas but| don't know if I had to add -s to guapa as well or nah same problem with sentence number. 2
2.La lengua importante-
*I know I have to start with las lenquas but again should I change importante as well or eave it alone
And this is my problem -if I should change adjective or no.
PIs help asap.

Answer 1

1) Unas muchachas guapas
2) Las lenguas importantes

And I don’t get the last one about adjectives