75-- According to the figure, a free piston with weight $W = 40\ \text{N}$ contains an ideal gas and the air pressure is $10^5$ pascals. On the piston, a weight of 80 newtons is placed; at constant temperature, the weight comes down $4\ \text{cm}$ and again reaches equilibrium. What is the base area of the piston in square centimeters?
[Figure: A rectangular container with a piston of weight $W$ on top, containing ideal gas, with height labeled $26\ \text{cm}$]
(1) $60$
(2) $40$
(3) $30$
(4) $20$
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\textbf{75--} According to the figure, a free piston with weight $W = 40\ \text{N}$ contains an ideal gas and the air pressure is $10^5$ pascals. On the piston, a weight of 80 newtons is placed; at constant temperature, the weight comes down $4\ \text{cm}$ and again reaches equilibrium. What is the base area of the piston in square centimeters?
\medskip
\textit{[Figure: A rectangular container with a piston of weight $W$ on top, containing ideal gas, with height labeled $26\ \text{cm}$]}
\medskip
\begin{tabular}{ll}
(1) $60$ \\
(2) $40$ \\
(3) $30$ \\
(4) $20$
\end{tabular}
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