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.

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.

metamorphism is the change of minerals or geologic texture (distinct arrangement of minerals) in pre-existing rocks (protoliths), without the protolith melting into liquid magma (a solid-state change). the change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. i hoped i !