Question 717630
Knowing there are 15 questions worth 3pts each means that there are 45 points in that section. (15*3=45)

In total your test is 100pts. Take the 45 away from the 100 possible (100-45=55). You have 55 remaining points left. 

Knowing that this portion of the test is work 11 points each, divide the remaining 55 points by the 11. (55/11=5)

There are 5 essay questions on the test.