Puzzle ZXEW 

Workings

Hint
How many days separate the two dates?

Answer
18 days.

Reasoning
There are 140 days between the two dates, and these 140 days are split in the following way:

   4 x Answer | 50 days | Answer

We already know about 50 days, so we have to split the remaining 90 days into the ratio 4:1, which is 72:18.

   72 days | 50 days | 18 days