Question 1077415
The equation shown comes from equating the distance.


{{{system(d=50(t-1),AND,d=30t)}}}


Two equations in the two unknowns, d and t.
Solve one of the equations for t, and substitute into the other equation; and solve for distance d.


{{{t=d/30}}}
-
{{{d=50(d/30-1)}}}
{{{d=50d/30-50}}}
{{{d=5d/3-50}}}
{{{3d=5d-150}}}
{{{2d=150}}}
{{{highlight_green(d=75)}}}----miles