akay wrote:Any ideas on solving this. Any formulas that one can use while solving coordinate geo. problems of this kind?

In the xy-coordinate system, if (a, b) and
(a + 3, b + k) are two points on the line defined by
the equation x = 3y – 7, then k =

(A) 9
(B) 3
(C) 7/3
(D) 1
(E) 1/3

well the formula is already given to you ..

substitute the values of x and y in the equation x = 3y-7 ... over here a=x and b =y ..

.. so we have a = 3b -7 .. (1)

Now, substituting the values (a+3,b+k) .. over here x = a+3 and y = b+k ..
so we have a+3 = 3(b+k)-7 .. a = 3b+3k-10 .... (2)

equating (1) and (2) we get 3b-7=3b+3k-10 .. that is 3k = 3 .. therefore k =1 ..

ok got it. appreciate your taking the time to help me.