Expand the following: \begin{align} x_1 &= \cssId{Step1}{\frac{-F_b1}{2m}t^2-\frac{gt^2}{2}sinα+v_0 t} \\[3px] &\cssId{Step2}{{} 0= \frac{F_b1}{m}t_s1-gt_s1·sinα+v_0 } \\[3px] &\cssId{Step3}{{} = ..Equation20..} \\[3px] \end{align}