Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Fact 1: volcanic ash in the atmosphere decreases the temperature by blocking the sun. 
Fact 2: Most volcanic ash consists of fine, dusty particles.
Fine, dusty particles erupted from volcanos decrease the temperature by blocking the sun.

Fact 1: DNA contains genetic instructions for proteins, and RNA helps assemble the proteins. 
Fact 2: DNA is the genetic material responsible for heredity.
The genetic material responsible for heredity contains instructions for proteins.

Fact 1: Reptiles are a class of tetrapod vertebrates that produce amniotic eggs. 
Fact 2: All reptiles produce eggs with a waterproof shell full of amniotic fluid.

Reptiles are a class of tetrapod vertebrates that produce eggs with a waterproof shell.