Answer: 5
Step-by-step explanation:
Let A denotes the number of major defects and B denotes the number of design defect.
By considering the given information, we have

Now, the number of major defects or design defects:

Also,

Hence, the number of design defects were major=5
Rectangle Formula: a = lw (Area = Length x Width)
Trapezium: A= a+b/2h (Area = Area + Base / 2 x h)
I hope this helps. :)