Since ¾ cannot be taken from ½ or ²/₄, add 1d. to both quantities, which will not alter their difference; or, which is the same thing, add 4 farthings to the first, and 1d. to the second. The pence and farthings in the two lines then stand thus: 7⁶/₄d. and 11¾d. Now subtract ¾ from ⁶/₄, and the difference is ¾ which must be written under the farthings. Again, since 11d. cannot be subtracted from 7d., add 1s. to both quantities by adding 12d. to the first, and 1s. to the second. The pence in the first line are then 19, and in the second 11, and the difference is 8, which write under the pence. Since the shillings in the lower line were increased by 1, there are now 14s. in the lower, and 5s. in the upper one. Add 20s. to the upper and £1 to the lower line, and the subtraction of the shillings in the second from those in the first leaves 11s. Again, there are now £20 in the lower, and £24 in the upper line, the difference of which is £4; therefore the whole difference of the two sums is £4. 11. 8¾. If we write down the two sums with all the additions which have been made, the process will stand thus:

225. The same method may be applied to any of the quantities in the tables. The following is another example:

From 7 cwt. 2 qrs. 21 lbs. 14 oz. Subtract 2 cwt. 3 qrs. 27 lbs. 12 oz.

After alterations have been made similar to those in the last article, the question becomes:

From7 cwt. 6 qrs. 49 lbs. 14 oz.
Subtract3 cwt. 4 qrs. 27 lbs. 12 oz.
The difference is4 cwt. 2 qrs. 22 lbs.  2 oz.

In this example, and almost every other, the process may be a little shortened in the following way. Here we do not subtract 27 lbs. from 21 lbs., which is impossible, but we increase 21 lbs. by 1 qr. or 28 lbs. and then subtract 27 lbs. from the sum. It would be shorter, and lead to the same result, first to subtract 27 lbs. from 1 qr. or 28 lbs. and add the difference to 21 lbs.

226. EXERCISES.

A man has the following sums to receive: £193. 14. 11¼, £22. 0. 6¾, £6473. 0. 0, and £49. 14. 4½; and the following debts to pay: £200 . 19. 6¼, £305. 16. 11, £22, and £19. 6. 0½. How much will remain after paying the debts?