1)
4 5/8-1 3/4 = 23/8
u can write 2 7/8
2)81.139
if u round any number to any place first find that place like tenth place .
then find the next number after this place .
here it is 3 after tenth place.
if a number in range 1-4 they dont need to round but if a number is 5-10 range ,round your number Up
answer is 81.1