East of 4 and N of 7 means it has traveled TWO ( 2 to 4) steps down and TWO(5 to 7) steps east
But it has to travel 3 steps from 2 to 5, so it will travel 3 to the east = 5+3=8

ofcourse it can be done by finding slope but easier to assimilate this way

B

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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Let’s rethink this problem as one that involves the equation of a line. Station 5 is the origin (0,0), and all other stations take on the traditional values on the x and y axes. Thus, when the boat leaves station #2, the ordered pair is (0,3), and the line of the boat’s path passes through the point (station #7, station #4), or (2,1). The line that connects these two points has a slope of (3 – 1)/0 – 2) = 2/-2 = -1. Using y = -1x + b, we substitute the values from (0,3), obtaining 3 = (-1)(0) + b, and so b = 3. Thus, the equation of the line connecting the two points is y = -x + 3.

We now plug in the ordered pairs of the answer choices to determine which of their equivalent ordered pairs satisfies the equation y = -x + 3.

Choice A: station #7 is at (2,0). Does 0 = -2 + 3? No.

Choice B: station #8 is at (3,0). Does 0 = -3 + 3? Yes!

Answer: B
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