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: Roundworms reproduce sexually. 
Fact 2: Nematodes are simple roundworms.

SOLUTION: nematodes reproduce sexually.

PROBLEM: Fact 1: Pedigrees are useful tools for studying inheritance patterns. 
Fact 2: Pedigree charts are a graphical way to represent the ancestry of an individual.

SOLUTION: charting ancestry on a graph is a useful tool for studying inheritance patterns.

PROBLEM: Fact 1: coal is used to produce electricity by burning in coal-fire power stations. 
Fact 2: Coal-fired power plants also contribute heavily to global warming.

SOLUTION:
Producing electricity by burning coal contributes to global warming.