Based on his experience, the manager has set the following priorities for the investment:

$(1)$ The total amount invested should be at least $$90,000.($d$1)$

$(2)$ The minimum annual average growth rate in stock prices is $12\%.($d$2)$

$(3)$ The risk factor of all stocks should not exceed an average of $5.($d$3)$

$(4)$ The total annual return should be $$15,000.($d$4)$

The constraint for the risk factor can be written as: