A man walks 20km in 4 hours. Find his speed.

5 km per hour

Explanation: If you set up a unit rate, you can simplify to find the answer.

20 km               ?

  =

4 hr                 1 hr

Use the crisscross method, so 20 times 1 is 20, and 20 divided by 4 is 5, so the answer is 5 km per one hour.

the correct answer in apex is tissue development, i know because i just had this question

above statement is not a true statement about the open ocean because the open ocean has low levels of nutrients. most of the photosynthetic activity on earth occurs in the open ocean within the photic zone. organisms in the deep ocean are exposed to frigid temperatures and total darkness but it does not begin at the low-tide mark.