鉛筆とペンを買いました
エンピツとペンをかいました。
Enpitsu to pen wo kai mashita.
could you also say えんぴつもペンも買いました?
Could 複数の be used to specifically clarify you did buy more than one pen & pencil? Google translate seems to think so, but it's hard to get a sense of whether it's an everyday conversational sort of term.