Question 1013232
{{{(18s^8d^9-21s^6d^7+12s^4d^5)/3s^4d}}}
Each term in the NUM is divided by the DEN.
= {{{18s^8d^9/3s^4d - 21s^6d^7/3s^4d +12s^4d^5/3s^4d}}}
Subtract exponents when dividing.  eg, {{{s^8/s^4 = s^(8-4) = s^4}}}
= {{{6s^4d^8 - 7s^2d^6 + 4d^4}}}