<h2>Answer</h2>
Cost of lectures = $7.33 per hour
<h2>Explanation</h2>
Let  the cost of the exam hours
 the cost of the exam hours 
Let  be the cost of the workshop hours
 be the cost of the workshop hours
Let  be the cost of the lecture hours.
 be the cost of the lecture hours. 
We know from our problem that exam hours cost twice as much as workshop, so:
 equation (1)
 equation (1)
We also know that workshop hours cost twice as much as lecture hours, so:
 equation (2)
 equation (2)
Finally, we also know that 3hr exams 24hr workshops  and 12hr lectures cost $528, so:
 equation (1)
 equation (1)
Now, lets find the value of  :
:
Step 1.  Solve for  in equation (3)
 in equation (3)

 equation (4)
 equation (4)
Step 2. Replace equation (1) in equation (4) and simplify



 equation (5)
 equation (5)
Step 3. Replace equation (2) in equation (5) and solve for 







Cost of lectures  = $7.33 per hour