This is almost identical to the official GMATPrep problem here:
https://gmatclub.com/forum/in-the-xy-co ... 93771.htmlThe best way to answer questions like this is to draw diagrams to see what possibilities there are. Here, we know our lines meet at some point in the first quadrant. We want to know if the two lines are either both rising or both falling (then their slopes would have the same sign, and so would give us a positive product).
If Statement 1 is true, one x-intercept is left of the origin, one is right of the origin. If a line has a negative x-intercept, and then rises to some point in the first quadrant, it must have a positive slope. But for the other line, we can't be sure - the slope can be positive or negative depending where the x-intercept is.
If Statement 2 is true, both y-intercepts are either above the origin or below the origin. If both are below, then both slopes are positive. But if both are above the origin, we can't be sure if we have negative or positive slopes.
Using both Statements, from Statement 1, as explained, we know one line has a negative x-intercept and a positive slope. So it must have a positive y-intercept. From Statement 2, the second line must have a positive y-intercept too, and a positive x-intercept from Statement 1. That line must be falling as it moves right, so must have a negative slope. So using both Statements, we can be sure we have slopes of opposite signs, and the answer is C.
Obviously a lot faster just to draw the diagrams than to write up the solution in words.