Given,
The amount paid on internship is $75.
The amount paid on internship of per week is $320.
The total amount of training and intership is $2635.
The number of weeks is x.
The expression of training and internship is,
[tex]\begin{gathered} 2635=320\times x+75 \\ 2635-75=320x \\ \frac{2560}{320}=x \\ x=8 \end{gathered}[/tex]Hence, the training for 8 weeks.