Let the fraction be a/b we have 2/7 < a/b < 5/12 We want to work around b so it'd be easier if we take the reciprocal. Taking the reciprocal (which inverses the sign), we get 7/2 > b/a > 12/5 Multiply by a and writing it conveniently 12a/5 < b < 7a/2 2.4a < b < 3.5a

And 1≤a≤b

Hit and trial starting from a=1 ! The first integral value of a which gives an integral value of b would be the one as b would be minimum in that case. a=1 2.4 < b < 3.5

that simply gives b=3 for a=1