It is for my final, please help!

Me ! write an equation for the interior angles of this triangle that uses the triangle sum theorem

Find the equation using the point (4,8)

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?