Rule twenty - one - if there are many equations of this sort , they should all be reduced to a single one , viz . to the equation whose terms occupy fewer places in the series of magnitudes which are in continued proportion , i . e . the series in which the order of the terms is to be arranged 如果有同種類的許多等式,就應(yīng)該化簡到一個等式,也就是說,化簡到在連續(xù)比例中量的系列里只有少數(shù)項,換言之,在此系列中,項目的秩序被安排好了。