The half-life of thorium-227 is 18.72 days. how many days are required for three-fourths of a given amount to decay?
i'm not quite sure how to set it up to even start working it? would be appreciated!

The graph above shows how the price of cell phones varies with the demand quantity. the equilibrium price for cell phones is where both supply and demand quantities equal $100, 5,000 5,000, $100

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space

What is the most important factor in determining climates.