OPTION 1

SELECT round(AVG(`infos_notes`.`total_notes`/`infos_notes`.`total_coef`, 1)) FROM `infos_notes` 
WHERE `infos_notes`.`idinfo_note`='%ID%'



OPTION 2

SELECT ROUND(AVG(`infos_notes`.`total_notes`/`infos_notes`.`total_coef`),2) FROM `infos_notes`
WHERE `infos_notes`.`idinfo_note`='%ID%'




SELECT SUM(`releve_notes`.`note`,2) FROM `infos_notes`
LEFT JOIN `releve_notes` ON `releve_notes`.`link`=`infos_notes`.`idinfo_note`
WHERE `infos_notes`.`idinfo_note`='%ID%'