Expand the following: \begin{align} &\cssId{Step1}{{ t_{bat,4}=?}}\\[3px] &\cssId{Step2}{t_{bat,4} =c_{bat}\over 3 I_{LED,4}}\\[3px] &\cssId{Step3}{t_{bat,4}= 133,3 h }\\[3px] \end{align}

- In the first step we make the equation of the force breaking with mass and acceleration
- In the seconde step we make the equation of normal force and the gravity force
- In the third step we make the equation of accelation with Force breaking and mass