-9
Sixteen.
16 minus 21 is -5
negative six
eleven
We convert into like terms giving sixteen twentieths minus five twentieths, giving eleven twentieths.
Twenty five minus one third is 24 and 2/3. You may have also meant twenty five minus one third of twenty five. That would be 16 and 2/3.
400
15
16.25
twenty-five
fourteen
1 minus 25/28 is 3/28