Data Suff questions

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Posted by: vik76gosai

1. In the xy-coordinate plane, the slope of line l is 3/4. Does the line l pass through the point (-2/3, 1/2)?
(1) Line l passes through the point (4, 4)
(2) Line l passes through the point (-4, -2)

2. If a and b are positive integers, what are the coordinates of the midpoint of line segment CD in the xy-lane?
(1) The coordinates of C are (a, 1-b)
(2) The coordinates of D are (1-a, b)

3. If x and y are integers, what is the value of x+y?
(1) 690<x<y<696
(2) ) 692<x<y<695

Thanks for your help!

1 - Q) y=l*(x-x0)+y0 - this is the equation of a line
if you know the slope of the line and one of its point, you can find the equation of the line. Once you found the equation, you can tell whether it passes through a defined point or not, thus any of the answer is sufficient - D

2 - Q) surely none alone is suff, therefore try checking both of them.
the mid of coordinate x equals (a+1-a)/2=1/2
the mid of coordinate y equals (b+1-b)/2=1/2
thus both together are sufficient - C

3) first isn't suff
second is suff - only possible values of x and y are 693 and 694 correspondingly

Thank you so much

1: D
2: C
3: B