Heya!!!
Answer to your question: 
Slope intercept form is represented as
y=mx+c
Line is parallel to y=3x-9 
so equation of line will be
y=3x+k -----(i)(where k is intercept)  
as slope of parallel lines are equal .
Since this line passes from (-2,4) , this point must  follow the equation of line. 
4=3 (-2)+k
4=-6+k
k=4+6
k=10
Putting value of k in (i),
y=3x+10
This is the required equation.
Hope it helps *_*