Doris Invested Some Money at 7% and Some Money at 8

Multiple Choice

Doris invested some money at 7% and some money at 8%. She invested $5,000 more at 8% than she did at 7%. Her total yearly interest from the two investments was $850. How much did Doris invest at each rate?

A) $4,000 at 7%, $8,000 at 8%
B) $3,000 at 7%, $9,000 at 8%
C) $3,000 at 7%, $8,000 at 8%