Verbs in the Haeyoche speech level follow these rules of conjugation:

1) -hada → -haeyo

Verbs that end in -하다 (-ha-da) (verb 하다 itself means to do) is conjugated as -해요 (-hae-yo).

공부하다 gong-bu-ha-da → 공부해요 gong-bu-hae-yo
주문하다 ju-mun-ha-da → 주문해요 ju-mun-hae-yo

2) -ada / -oda → -ayo / -oayo

Verbs that have vowels ㅏ (a) and ㅗ (o) as the last character of the stem have the ending ㅏ요 (-ayo) added.

가다 gada → 가 ga + 아요 ayo → 가요 gayo
보다 boda → 보 bo + 아요 ayo → 봐요 boayo

3) -da → -eoyo

All other verbs are conjugated as ㅓ요 (-eoyo).

For verbs that have vowels other than ㅏ and ㅗ at the end of the stem:

마시다 masida → 마시 masi + 어요 eoyo → 마셔요 ma-syeo-yo (because 시 si + 어 eo makes 셔 syeo)
배우다 bae-u-da → 배우 bae-u + 어요 eoyo → 배워요 bae-wo-yo (because 우 u + 어 eo makes 워 wo)

For verbs that have a consonant at the end of the stem:

먹다 meokda → 먹 meok + 어요 eoyo → 먹어요 meokeoyo
읽다 ikda → 읽 ik + 어요 eoyo → 읽어요 ikeoyo