aps_can wrote:

if a nad b are +ve integers, what isthe value of a+b?

1) a/b=5/8

2)The greatest common divisor of a and b is 1

please explain the answer.

What does "Greatest common divisor is 1 " imply???????

It means that the only common factor is 1.

from 1, we only know that ratio , not the numbers ..insufficient

from 2, we know that the greatest common divisor is 1...we can have for eg... 5 and 8, 5 and 9 ,5 and 11, 5 and 13 , 3 and 11...so insufficient

combine...the numbers can be

5 and 8 => G.C.D = 1

10 and 16 => G.C.D = 2

15 and 24 => G.C.D = 3

20 and 32 => G.C.D = 4

so on ...so we have only two numbers that satisfy the ratio condition and the G.C.D condition

Answer C

Thanks

Praetorian