An equivalent fraction for 1/2 would be 2/4. This is because you can simplify 2/4 by dividing it by 2. The final answer would be 1/2.
An equivalent fraction for 4/5 would be 8/10. It's basically the same thing. Divide them both by 2 and you'll get 4/5 since 8 divided by 2 is 4, and 10 divided by 2 is 5.