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Why are reflecting telescopes cheaper to build than refracting telescopes?
US$
The symbol for the United States Dollar, the currency of the United States.
Metric Tonne
A unit of mass equivalent to 1,000 kilograms or approximately 2,204.6 pounds.
US$
The abbreviation for United States Dollar, the official currency of the United States.
West Virginia Coal
Coal mining industry in the state of West Virginia, known for its significant contribution to the US coal supply.
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