Let's call H the number of hours she dances. So, one group of sponsors will donate a total, in dollars:
[tex]6H[/tex]Also, the other group of sponsors will donate a total, in dollars:
[tex]75[/tex]So, she will make:
[tex]6H+75[/tex]For that value to be at least $500, we have:
[tex]6H+75\ge500[/tex]Now, we can find the number of hours Trace should dance if she wants to raise at least $500 by solving the above inequality.
We obtain:
[tex]\begin{gathered} 6H+75\ge500 \\ \\ 6H\ge500-75 \\ \\ 6H\ge425 \\ \\ H\ge\frac{425}{6} \\ \\ H\ge70.83 \end{gathered}[/tex]Therefore, she should dance for at least 70.83 hours. Rounding to the nearest integer hour, we can say she should dance for at least 71 hours.