TASK DEFINITION: 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.
PROBLEM: Fact 1: gravity causes objects that have mass to be pulled down on a planet. 
Fact 2: Weight is the measurment of the force of gravity on a mass.

SOLUTION: Weight is measured when objects are pulled down by gravity.

PROBLEM: Fact 1: Evolution occurs by a process called natural selection. 
Fact 2: Adaptation and natural selection are discussed.

SOLUTION: Evolution occurs by a process of adaptation.

PROBLEM: Fact 1: Reptile parents provide little if any care to their young. 
Fact 2: Iguanas are good reptiles for experienced reptile caretakers.

SOLUTION:
iguana parents provide little care to their young.