The Rio Credit Union has $$250,000$ available to invest in a $12-$month commitment and wants to invest all of it$.$ The money can be placed in Brazilian treasury notes yielding an $10\%$ return or in riskier high$-$yield bonds at an average rate of return of $9\%.$ Credit union regulations require diversification to the extent that at least $40\%$ of the investment be placed in Treasury notes. It is also decided that no more than $40\%$ of the investment be placed in bonds.

The aim of the objective function for Rio Credit Union should be to Maximize the objective value.

The optimal ROI occurs when:

$ invested $in$ Treasury notes $=(enter$ your response $as$ a whole number$).$