Thanks please can you give out how to balance chemical equation

Thanks please can give how to balance chemical equation

Calculations  
P1V1=P2V2,       P1= 2 atm, p2= 4 atm ,V1=1.5 , V2=?,   [2×1.5] ÷4.=0.75. QED

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<html><body>A gas occupies a volume of 1.5 liters at a pressure of 2 atmospheres. If the pressure is increased to 4 atmospheres while the temperature remains constant, what will be the new volume of the gas?</body></html>

Earlier discussion