Flower bed is in the shape of a triangle with one side twice the length of the shortest side, and the third side is 15 feet more than the length of the shortest side. find the dimensions if the perimeter is 143 feet

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?