Find the distance from the point P(6, 9 ) to the line y = 3 - 3x.

recall that distance from (a,b) to Ax + By + C = 0

= |Aa + Bb + C|/√(A^2 + B^2)

so you have
3x + y - 3 = 0, and the point (6,9)

go for it