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RULE OF TIIREE DIRECT. TIF Rule of 'Threr Direct leachas, los having three numbers given to find a fourts, which shall have the same Oroportion to the thiril, as tlie second has to tie first. . 1. coloserve that two of the given numbers in you question are always of the same name, or kind; one of which must be the first number in staring, and the oil.ee the thirol number ; consequently, the first and thired amming bers must always be of the same name, or kind: and the other number, i hich is of the saine kind with the answer, or thing smuglit, will always possess llic secund or middle place.
2. Tlie rniril term is a demand; and may be known by these vrtice like words before it, viz.. What will : What cost: low many flow far: llow long? ur, lluw. much ? &c.
RULE. 1. State the question : that is, place, the numbers so that the first and thirel terms may be of the same kind; and tie second term of the same kind with the answei, ur thing sought.
2. Bring the first and third terms to the same denom. inatiovi, and rerlisce t.e second term to the lowest name nientioned in it.
3. Jiultiply the second and third terms together, and divide their product by the first term ; the quotient will be the answer to the question, in the same denmination you left the second term ili, which may be brought into any ouiicr denomination required.
'The methoci of proof is by inverting the question.
NOTE.-The following methods of operation, when they can be usest, perform the work in a mu::h shurier manner than the oneral rules
1. Diviide the second terin by the first : multiply the quu. tist i icin the third, and the product will hr the alisierOr
?. Diviele ihe ihiril térmiling the first: inultiply the promotions min tim Borovni. a ved the produe: will lop the winner. ()
3. Divide the first soorin any use second, and the thired by That qiwtient, and the la-t gloriant will be the answer. Or 4. Divide the first terin by the thiril, and the second by
uotient and the last uotient will be wie answet.
1. If 6 yariis of cloth cost 9 dollars, what will 20 yards cost at the saine rate :
I'ds. 8 Ias. Here 20 yards, which moves 6:9:: 20 the question, is the third term; 6 vils. the same kind, is the first, and 1 dollars the second.
FEDERAL MONEY. NOTE 1. You must state the questioni, as tangit in the Rules foregoing, anil alier reilucing the first 2011 thi:rt teras to the same name, &c. S'oru max munols and die vide according to the rules indecimals; 11 by the rules 1
y multiplying and divieling Ewuleral Mouey.
Ans. 26.52-826, 32c1s. But any sum in dollars and cents may be written down as a whole number, and expressed in its lowest denomi. nation, as in the following example: See Kvilurtion of Foderal Money, page 67.)
20. What will i qr. 9 lb. sugar come tv, at 6 du!lars 43 cis. per cnt . yr. 1b.
lb. ri's. lb. 19
As 112 : 645 : : 37
37. 57 26.
oets, 112325&S(213+ Ans. S8,18
NOTE . When the first and third numbers are rede. ral money, you may all ex cozilers, (if necessary) until you make !eir decimal places or livres at the i.g1:1, land of the separatris, qual: which will reclince then to
like denomination. Thier: vols nav multiple and di. jele, as in whole numbers, and the quotient will express be answer in the least denomination mentioucd in the cond, or mislille terin
21. If s dollars will huv 7 yards of cloth, how many yards can I buy for 120 dollars, 75 cents ?
cts. yds. cts. As 500 : 7 : : 12075
$ cts. 23. If a man lays out 121, 23 in merchandize, and thereby gains 39 dollars, 51 cis, how much will he gave by laying out 12 dollars at the same rate s .
Cents. cents. cents.
cts. 8 cts.