What is four fifths minus a half?

Answer 1

We are dealing with the fractions 4/5 and 1/2. In order to use arithmetic on them, they have to be in the same terms . . . the denominator or bottom number must be the same in both fractions, but without changing their values.

One way to get a common (same) denominator is to simply multiply them together. Doing that (5 times 2) gives us 10. So 4/5 becomes 8/10 and 1/2 becomes 5/10. Then, 8/10 minus 5/10 is 3/10, which is your answer.