For this case you can solve the problem by applying a simple rule of three in which we have
520 ---> 100%
800 ---> x
Clearing x we have
x = (800/520) * 100 = 154%
the percentage increase in cost was
154-100 = 54%
answer
the percentage increase in cost was 54%
65,759.60
Hope this helps
The absolute value of an given number is always positive. So, when adding two to any positive number will always be greater than the number by itself.