It looks like we are solving for a pressure. All that is required is some algebraic manipulation to find our pressure in mmHg.
Given:
(5.0 m³)(7.5 mmHg) = (P)(4.0m³)
Multiply:
37.5 = 4.0P
Divide:
9.375 = P
P = 9.4 mmHg (remember sig figs)
Answer:
9.4 mmHg
