what do we do when slope of 1 line is, say -5, whereas other line has slope +3. Do we consider sign or just the absolute value? How to know which is used when?
I think you are confused between the english meaning of the word "regression" and the mathematical meaning of the word "regression", and if you are not. I am still going to state it who is having a bad time understanding it.
"Regression line", is nothing but a line plotting the points on the graph based on the relationship, it is not certain that each point will pass through that line but it was "expected" to pass that line based on all the data points given.
Now, even if the slope of the ice cream line in absolute terms was more than the cheese line, then that might have created a confusion for a non-mathematical person as to whether that slope is negative or positive and that a negative number is always less than a positive number.
But in absolue terms if we are not even consider that one has a negative trend and the other has a positive trend. It is pretty clear that the cheese line is moving upwards at a faster rate, hence it has more slope than the ice cream line which is decline at a slower rate.
Hence, the ice cream line has less slope in both the cases regardless of whether you consider sign or not.
That's why i feel you were confused between what regression actually meant, it is not asking which of the slope is declining. It is asking that which line is more rapidly changing it's value and it could be in either direction.
ayooohelp
I feel like one of my biggest barriers on certain GMAT questions is understanding what the test has in mind when it says something. For instance, how am i supposed to know its a "less than" slope of regression and not a greater than. If I am to believe a slope of regression is how much something is shrinking, its very feasible to a shrinking slope as a positive regression, making the answer greater than, since regression has a negative built into it. I selected greater than for that exact reason. A greater slope of regression would mean its more negative (at least its feasible to paint it like that). Any tips and tricks to interoperate lines like this which can truly go either way?