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2)insuff, this is saying that greatest common factor of a and b is 1
ex. 12 and 7 or any prime number pair ( ex. 2 and 5)

together

5/8= a/b : answers have to be multiples of the numberator and denominator. ex. 10 and 16 or 15 and 24. These answers have common factors. Since 5 and 8 are in its most simplified fraction form, it has to be the answer.

If you can explain it better please let us know. thanks

If a and b are positive integers, what is the value of a + b? 1) a/b = 5/b 2) the greatest comon divisor of a and b is 1

make sure your OE follows your question.

joemama142000 wrote:

Here is my explanation: 1) insuff, dont know what a or b are 8a=5b 2)insuff, this is saying that greatest common factor of a and b is 1 ex. 12 and 7 or any prime number pair ( ex. 2 and 5) together 5/8= a/b: answers have to be multiples of the numberator and denominator. ex. 10 and 16 or 15 and 24. These answers have common factors. Since 5 and 8 are in its most simplified fraction form, it has to be the answer. If you can explain it better please let us know. thanks

Anyway, here is the original question and explanation. I thought it was tricky.

If a and b are positive integers, what is the value of a + b ?
(1) a/b=5/8
(2) The greatest common divisor of a and b is 1.

Here is my explanation:

1) insuff, dont know what a or b are 8a=5b

2)insuff, this is saying that greatest common factor of a and b is 1
ex. 12 and 7 or any prime number pair ( ex. 2 and 5)

together

5/8= a/b : answers have to be multiples of the numberator and denominator. ex. 10 and 16 or 15 and 24. These answers have common factors. Since 5 and 8 are in its most simplified fraction form, it has to be the answer.

Anyway, here is the original question and explanation. I thought it was tricky.

If a and b are positive integers, what is the value of a + b ? (1) a/b=5/8 (2) The greatest common divisor of a and b is 1.

Here is my explanation:

1) insuff, dont know what a or b are 8a=5b

2)insuff, this is saying that greatest common factor of a and b is 1 ex. 12 and 7 or any prime number pair ( ex. 2 and 5)

together

5/8= a/b : answers have to be multiples of the numberator and denominator. ex. 10 and 16 or 15 and 24. These answers have common factors. Since 5 and 8 are in its most simplified fraction form, it has to be the answer.

SORRY! if i'm asking a silly question...

since a/b = 5/8. why can't we just plug in a = 5 and b = 8? Pls explain. thanks!

consider a/b=5/8 if u consider some other number 25/40 and simplifying it would also get 5/8 so the value given might not ration not the original value
_________________

Regards, Harsha

Note: Give me kudos if my approach is right , else help me understand where i am missing.. I want to bell the GMAT Cat

Anyway, here is the original question and explanation. I thought it was tricky.

If a and b are positive integers, what is the value of a + b ? (1) a/b=5/8 (2) The greatest common divisor of a and b is 1.

Here is my explanation:

1) insuff, dont know what a or b are 8a=5b

2)insuff, this is saying that greatest common factor of a and b is 1 ex. 12 and 7 or any prime number pair ( ex. 2 and 5)

together

5/8= a/b : answers have to be multiples of the numberator and denominator. ex. 10 and 16 or 15 and 24. These answers have common factors. Since 5 and 8 are in its most simplified fraction form, it has to be the answer.

SORRY! if i'm asking a silly question...

since a/b = 5/8. why can't we just plug in a = 5 and b = 8? Pls explain. thanks!

thanks. good explanation indeed. never think of it...