\begin{align} \text{Per a calcular la superfície s hem de} :&\cssId{Step1}{P_{h}=\frac{W}{t}}\\[3px] &\cssId{Step2}{P_{h} = p*q }\\[3px] &\cssId{Step3}{q =\frac{V}{t} }\\[3px] &\cssId{Step4}{P_{h} = p*\frac{V}{t} }\\[3px] &\cssId{Step5}{\frac{W}{t} = p*\frac{V}{t} }\\[3px] &\cssId{Step6}{p=\frac{W}{V} }\\[3px] &\cssId{Step7}{p=\frac{4,651·10^6}{45,6} }\\[3px] &\cssId{Step8}{p=1,020·10^5=1,020Pa }\\[3px] \end{align}