RULE.--_Find the rate per cent that each investment yields, by rule,
under item 2; then compare rates._
EXAMPLE: Which is the better investment; 6% mortgages at 10% premium, or
5% bonds at 10% discount?
(1) 110)600(5-5/11%.
(2) 90)500(5-5/9%. 5/9 - 5/11 = 10/99, practically 1/10.
_Ans._ The latter, by 1/10 of 1%, nearly.