instruction:
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.
question:
Fact 1: a calculator is used for adding. 
Fact 2: Calculator performs basic arithmetic, such as addition and subtraction.
answer:
arithmetic includes uses for subtraction.


question:
Fact 1: using renewable resources to generate power reduces greenhouse gases. 
Fact 2: Nuclear power generation plants emit no greenhouse gases.
answer:
Nuclear power plants reduce greenhouse gases.


question:
Fact 1: the vanes rotating in an electric fan causes air to move. 
Fact 2: Output of the fan is varied by means of a series of adjustable vanes upstream of the impeller.
answer:

by adjustable rotating in an electric fan air output of the fan is varied.


