Data Sufficiency

Is x > y ?

1) (2/5) x > (3/8) y

2) (3/7) x > (15/29) y

OA: C
Source: Expert Global

My approach

1) (2/5) x > (3/8) y
Simplifying

16x > 15y

Let x =y=1.................16>15.........answer is No

Let x =2 &y=1.................32>15.........answer is Yes

Insufficient

2) (3/7) x > (15/29) y
Simplifying

29x > 35y

Let x =y=-1.................-29>-35.........answer is No

Let x =2 &y=1.................32>15.........answer is Yes

Insufficient

My problem starts here
combine 1 & 2

As the sign is same direction we can add both in inequalities

45x > 50 y......9x > 10y

Let x =y=-1.................-9>-10.........answer is No

Let x =2 &y=1.................18>10.........answer is Yes

Answer is E.

However, the OA is C

1- Why combing both inequalities did not help here? While it helps in other situation when combing both statements like the following question:
Is xy >0
1) 3x -y >0
2) 3x - 2y < 0
After combing subtracting 1 from 2........we can safely say that y > 0 and then from 1, we can deduce e that x >0.

2- What is the best when combining such inequalities for question at hand?