A financial planner has a client with ​$19,000 to invest. If he invests​ $10,000 in a certificate of deposit paying 11​% annual simple​ interest, at what rate does the remainder of the money need to be invested so that the two investments together yield at least $1640 in yearly​ interest?

For the two investments to yield at least $1640 in yearly interest the remainder of the money needs to be invested at a rate of at least %.