Answer:
The initial amount, 1.3 million = 1,300,000 is the 100%.
now, 640,000 is a given percentage (lower than 100%) of that.
How we can find it?
suppose that 640,000 represents an x%.
Then we have that the quotient between the actual quantities and the percentages must be the same
(640,000/1,300,000) = x%/100%
x% = (640,000/1,300,000)*100% = 49.23%
Then the percentage declined is:
100% - 49.23% = 50.77%
The other question can not be answered with the given information.