Can you help me about algebra grade 10?

Premium gasoline sells for 78.9 cent /L.regular gas sells for 71.9c/L. To boost sales, a middle octane gasoline is formed by mixing premium and regular. If 1000 L of this middle octane gas is produced, and is sold at 73.9cents /L, then how much of each type of gasoline can you assume was used in the mixture?