Respuesta :

9 because every ten plants is equal to 3 gallons. 30 plants are equal to 9 gallons.
tell me if if helps.
Kwang
9 because if you divide 6 by 2 you get 3 and if per 10 plants you have to use 3 gallons then for 30 you'll have to use nine because 3x3 equals 9