Expand the following: \begin{align} a= \frac{F_b}{m} =&\cssId{Step1}{v(t)=ad}\\[3px] &\cssId{Step2}{v(t)= -\frac{F_b}{m}d}\\[3px] &\cssId{Step3}{v(t)= -\frac{F_b}{m}t+K}\\[3px] &\cssId{Step4}{v(t)= -\frac{F_b}{m}t+v_0}\\[3px] \end{align}