2/5 + 3/12 = 24/60 + 15/60 = 39/60 = 13/20 = 0.65
We convert this to twelfths to give: 10 twelfths + 4 twelfths + 9 twelfths = 23 twelfths or 1 and 11 twelfths.
One fourth is three twelfths. So one twelfth plus three twelfths is four twelfths, which is also one third.
six tenths or three fifths
3 5/8 + 5/12 is 4 1/24.
three fifths plus one quarter = 17 twentieths
5
7 4/5
They would have to convert to same denominators to add. So that would be 8 twelfths plus three twelfths. And that is eleven twelfths. 0.916666667
Seven-twelfths
13 and 1 fifth
this is the same as 3 holes and 8 twelfths plus 1 hole and 3 twelfths = 4 and 11 twelfths
3/4
five twelfths
We convert this to twelfths to give: 10 twelfths + 4 twelfths + 9 twelfths = 23 twelfths or 1 and 11 twelfths.
The sum is 23/30
twelve and four twelfths
four fifths is equal to eight tents, so three tenths plus eight tenths is eleven tenths, or one and one tenth