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The two digits in the numerator of a fraction whose value is 4/7 are reversed in its denominator. The reciprocal of the fraction is the value obtained when 16 is added to the original numerator and 5 is subtracted from the original denominator. Find the original fraction

2007-04-17 05:07:40 · 8 answers · asked by Anonymous in Science & Mathematics Mathematics

8 answers

ans 12/21

method
let x be 10's digit {numerator}
let y be units digit {numerator}
then numerator is 10x +y
and denominator is 10y+x
10x +y +16 = 10y+x-5
9x-9y=-21

2007-04-17 05:19:02 · answer #1 · answered by Anonymous · 0 0

Ok first is the first part, so a 2 digiit number in numerator which is reversed in the denomiter and is equal to 4/7. Well first you take 4/7 and times the numerator and denomitar by 3 so its 12/21. Then you find the reciprocal which is 21/12. Then since the original+16=21 The original Numerator is 5. then the Original Denomitor-5=12, so the original Denomitor is 17. So the Original Fraction is 5/17

2007-04-17 12:15:15 · answer #2 · answered by phasetwin 1 · 0 1

Done as Algebra, 1st statement says

(10a+b)/(10b+a) = 4/7
40b + 4a = 70a + 7b
33b = 66a
b = 2a

2nd statement says

(10a + b + 16)/(10b + a - 5) = 7/4
40a + 4b + 64 = 70b + 7a - 35
33a - 66b = -99
2b - a = 3

substituting,

2(2a) - a = 3
4a - a = 3
3a = 3
a = 1
b = 2(1) = 2

fraction is 12/21

granted, 4/7 = 8/14 = 12/21 is simpler, but that's not the point of this kind of question.

2007-04-17 12:29:54 · answer #3 · answered by Philo 7 · 0 0

Let u = the units digit and t = 10's digit of numerator.
Then (10t +u)/(10u+t) =4/7
40u+4t = 70t +7u
66t -33u =0
2t-u =0 <-- Eq1
(10t+u+16)/(10u+t -5) = 7/4
40t+4u+64= 70u +7t-35
33t -66u = -99
t-2u =-3 <-- Eq 2
-2t+4u =6 <-- Eq 3
Add Eq1 and Eq2 getting
3u = 6
u = 2
So t +4 = -3 --> t =1
So answer is 12/21

2007-04-17 13:16:11 · answer #4 · answered by ironduke8159 7 · 0 0

12/21 is the original fraction.

21/12 is the reciprocal fraction.

2007-04-17 12:11:08 · answer #5 · answered by charmedchiclet 5 · 1 0

22

Now, if you want the real answer you need to do your own homework so that you understand the lesson being taught.

2007-04-17 12:10:53 · answer #6 · answered by kja63 7 · 0 2

um i dont know

2007-04-17 12:10:12 · answer #7 · answered by mai d 1 · 0 2

*retarded face* uhhhh i dont know *shurgs*

2007-04-17 12:10:57 · answer #8 · answered by slipknot freak 2 · 0 2

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