If one fourth of the mammals on Earth are bats what fraction of mammals are not bats?

If one fourth (1/4) of the mammals are bats, then the mammals that are not bats would be 3/4 of all mammals on Earth.

Rationale:

The whole is (all the mammals on Earth) = 4/4,

1/4 = bats

4/4 - 1/4 = 3/4 of the total mammals are not bats

You could also calculate this in percentages.

For example:

The whole (all the mammals on Earth) = 100%

1/4 = bats

100 divided by 4 = 25

100% - 25% = 75% of the total mammals are not bats