Question

If the question is 11x + 15y +23 = 0 , 7x -2y -20= 0 Find x and y. In any this type of sum how can we now that first we have to find the value of x or y .

Answer 1

You can find any value , either x or y first as you wish.
Finding value of either one will give value for the other one.

So, Considering equations 11x + 15y +23 = 0 , 7x -2y -20= 0

11x + 15y + 23 = 0.......(1)
7x - 2y - 20 = 0..........(2)

Multiplying (1) by 7 and (2) by 11 , we get,

77x + 105y + 161 = 0
77x - 22y - 220 = 0

Subtracting we get, 127y = - 381
y = -3

Subtituting y = -3 in (2) ...we get , 7x + 6 - 20 = 0
7x = 14
x = 2
Vice versa also we can Solve for x first subtitute value of x in (2) or (1) and find value of y