R<sub>1</sub>-TR<sub>0</sub>)</span>. So far only the first two equations in (3) are examined. There are two more conditions when we add the last equation into the mix. Substituting the general solution <span class="nowrap">N=R<sub>0</sub>+60m</span> into the last equation in (3) and following the same argument, we find the second necessary and sufficient condition: <span class="nowrap">g<sub>2</sub>|(R<sub>2</sub>-R<sub>0</sub>T)</span>, where <span class="nowrap">g<sub>2</sub>=gcd(60T,U)</span>. The last 