If a = (1,2), B = (- 1,0), C = (4,6) are given, and a and B are used to represent C, what is C

If a = (1,2), B = (- 1,0), C = (4,6) are given, and a and B are used to represent C, what is C

Let C = XA + Yb
=(x,2x)+(-y,0)
=(x-y,2x)
So X-Y = 4
2x=6
The solution of the equation is x = 3, y = - 1
So C = 3a-b