Expand the following: \begin{align} v= \frac{F_b}{m}t+v0 =&\cssId{Step1}{x(t)=v_td_t}\\[3px] &\cssId{Step2}{x(t)= -\frac{F_b}{m}t+v_0dt}\\[3px] &\cssId{Step3}{x(t)= -\frac{F_b}{2m}t^2+v_0t+C}\\[3px] &\cssId{Step4}{x(t)= -\frac{F_b}{2m}t^2+v_0t}\\[3px] \end{align}