Answer:
The first questions answer is No, because 1/2 converted to a fith is 2.5, so 2 fiths +2.5 fiths is 4.5 fiths vs 1 whole.
And to the second question the sum of 4/5 and 1/10 is closer to 1 than 1/2 because 1/10 + 8/10 ( which i turned 4/5 into a tenth) is 9/10 which is closer to One than 1/2