Transcript text: Li earns a salary of $\$ 6.80$ per hour at the video rental store, for which he is paid bi-weekly. Occasionally, Li has to work overtime (time more than 40 hours but less than 70 hours). For working overtime, he is paid time-and-a-half. Li's salary is given by the function
\[
S(t)=\left\{\begin{array}{ll}
6.8 t & \text { if } 0