An 1880 old war dollar coin was worth one dollar in its time as of 2015 it was considered a pawn item and is now worth double its value every year How can I turn this word problem into the equation f(x)=a x r^x
I need this for a project

The magnitude, m, of an earthquake is defined to be m=log l/s, where i is the intensity of the earthquake (measured by the amplitude of the seismograph wave) and s is the intensity of a “standard” earthquake, which is barely detectable. what is the magnitude of an earthquake that is 1,000 times more intense than a standard earthquake? use a calculator. round your answer to the nearest tenth.