Mr. sharon can paper a room in 3hrs. his assistant needs 5hrs. if mr. sharon works 1hr and then his assistant completes the job alone, how long will it take the assistant to finish the job?

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?