It's a linear function of the form y = m.x + b.
We know the value of the slope m = 6 (given), so the equation becomes:
y = 6.x + b. To calculate b, plug in (3,4), where x = 3 and y = 4
4 = 6(3) + b
4 = 18 + b and b = -14
Then the function is: y = 6.x - 14
