16 × 10 160
== 26⅔ Ans.
16 - 10 6

Example 40.—40's and 30's worsted are yarns in stock, find a third thread to fold with these to make a three-fold counts = 10's.

40 × 30 40 × 30
== 17⅐ counts of the two yarns folded.
40 + 30 70

Using the difference rule—

17⅐ × 10
= 24's Ans.
17⅐ - 10

To provide proof use the ordinary method of folding—

40 ÷ 40= 1lb.
40 ÷ 30= 1⅓lb.
40 ÷ 24= 1⅔lb.
40 hanks= 4lb.

40 ÷ 4 = 10's counts.

If the third thread were wanted in another quality such as cotton, the answer would be secured by transfer—

24 × 560
= 16's cotton
840