I'm assuming a typo here, where all of the figures are typed twice. So let the speeds of the trains be n and n+20. Then:
8n+8(n+20)=960
16n=800
n=50
n+20=70
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The correct option is this: THIS IS THE DEMONSTRATION OF BOYLE'S LAW. AS THE VOLUME INCREASES, THE PRESSURE DECREASES AND THE MARSHMALLOW WILL GROW LARGER.
Boyle's law states that the volume of a gas is inversely proportional to the pressure of the gas at constant temperature. The law explains the relationship between the volume and pressure of a gas at constant temperature.
Broad internalism, conventionalism, pluralistic internalism
The kinds of atoms in the substance and their arrangements