21.7 mL of gas at 98.8 kPa is allowed to expand at constant temperature into a 52.7 mL container. What is the new pressure of the gas?

40.7 kPa

Explanation:

P1 • V1 = P2 • V2

so ...

98.8 kPa (p1) • 21.7 mL (v1) = P2 (we don't know it) • 52.7 mL (v2)

Now you have to solve for P2 which is pressure, so just like an algebra equation, to get P2 by it self, you have to divide 52.7 mL from it.

(98.8 kPa • 21.7 mL) / 52.7 mL = P2

so ...

P2 = 40.7 kPa