The point (2 , 3) lies on the graph f(x) and g(x).

So we have 3 = a*2 + b - 9

and 3 = 2*b*2 - a

This gives us two equations to solve for a and b.

2a + b = 12...(1)

4b - a = 3 ...(2)

4b - a = 3

=> a = 4b - 3

substitute in (1)

2(4b - 3) + b = 12

=> 8b - 6 + b = 12

=> 9b = 18

=> b = 2

a = 4*2 - 3 = 5

**The required values are a = 5 and b = 2 **