Difficult questions on Process Costing

Hello Sir, I need your help with the following 2 questions:

The following information is available for a production process for the last period;
Material Input 200 kg @ $4 per kg
Labour Input 100 hrs @ $15 per hour
Dept Overhead $1000
Transfer to F.goods 150 kg
Normal loss is 10% of input. Losses are identified when the process is 50% complete. There is no opening or closing WIP.
The total cost of a completed unit is:
A. $22.00 B. $20.48 C. $19.59 D. $18.33

I am confused on the “losses are identified when the process is 50% complete” part.

Q2. Vare produces various inks at its Normanton factory. Production details for Process 1 are as follows:
Opening WIP, 1 April 400 units 60%
Closing WIP, 30 April 600 units 20%
Units started 1000; units finished 800
The degree of completion quoted relates to labour and overhead costs. “3/4 of materials are added at the start of the process and the remaining 1/4 is added when the process is 50% complete.” The company uses the FIFO method of cost allocation.

The equivalent units of production for materials in the period are:
A. 1250 B. 1000 C. 850 D. 650

I am again clueless on the the “50% complete part”.

I would really appreciate if you can help me on how to tackle these parts (if possible with some explanation) as well as the way to get the answer. Thanks!