Question 1095331
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<pre>
    Let C(t) be the non-linear function defined by these two lines

         
        C(t)  = 500,            if 0 <= t <= 2,

        C(t)  = 500+100*(t-2),  if t > 2.
         

    where t is the time in hours.


    Then the inequality the problem asks for is


        C(t) <= 900.


    The solution set for this inequality is the time interval [{{{0}}},{{{2 + (900-500)/100}}}],  which is [0, 6].
</pre>