separate the sentence with a line between the complete subject and the complete predicate

Question

Three-fourths of the earth / is covered by water, and most of it is salty ocean water.
is the line in this simple sentence correct??
THANKS

Answer 1

You've put the line in the right place in the first clause, but what about the second clause in that sentence?

Answer 2

This is not a simple sentence. It's a compound sentence with two subjects and two predicates.

http://www.eslbee.com/sentences.htm