Kevin is planting 15 bushes and 9 trees in rows. if he wants to be exactly the same with no plants left over, what is the greatest number of rows kevin can plant?

Becca wants to mix fruit juice and soda to make a punch. she can buy fruit juice for $3 a gallon and soda for $4 a gallon. if she wants to make 28 gallons of punch at a cost of $3.25 a gallon, how many gallons of fruit juice and how many gallons of soda should she buy?