One safe investment pays $8\%$ per year, and a more risky investment pays $9\%$ per year.

a$.$ How much must be invested in each account if an investor of $$100,000$ would like a return of $$8,220$ per year?

b$.$ Why might the investor use two accounts rather than put all the money in the $9\%$ investment?

a$.$ $$,$ is invested in the $8\%$ count.

$ is invested in the $9\%$ account.