Your simple answer will be Y = 3/5 x+3
Explain:
The two points on the graph = (-5,0) (0,3)
And then the Y intercept is the number 3 
**that is where it intersects on the Y Axis** 
So then the slope is....
change Y 
 0 to 3 up 3
(zero to three) and then (up three)
=3/5
Next...
change X 
 -5 to 0 Right 5
(negetive five to zero) and (Right five)
(the slope is a positive)
Now the Sloppe intercept is 
Y =mx+b
Y = 3/5 x+3
So that is your final answer :)
I hope that this helps 
If you have any questions im here to help :)