68.
If, in a parcel of old silver and copper coins, each silver piece is worth as many pence as there are copper coins, and each copper coin is worth as many pence as there are silver coins, there are eighteen silver and six copper coins, when the whole parcel is worth eighteen shillings.
69.
These are five groups that can be arranged with the numbers 1 to 11 inclusive, so that they are all equal:—
(82 - 52 + 1) = (112 - 92) = (72 - 32) = (62 + 22) = 4(10).
70.
John Bull, under the conditions given, lived to the age of eighty-four years.