Question 461839
{{{4/5b - 2/20b^2}}}

={{{4*4b/20b^2 - 2/20b^2}}}

={{{(16b - 2)/20b^2}}}

={{{2(8b - 1)/20b^2}}}

={{{cross(2)(8b - 1)/cross(20)10b^2}}}

={{{(8b - 1)/10b^2}}}