Question

-7 1/3 written as a fraction is?

Answer 1

In these mixed numbers the first part, so in this case -7 is the whole number part than the next fraction 1/3 is added to the number.
-7=-21/3
now add 1/3
-21/3 + 1/3=-20/3

Answer 2

I never understand as a maths uni student that why this mixed number is important. It is not convenient to use it.