y = 2x is the answer to 1).
y = 3x is the answer to 2).
The slope intercept for of the line for a given point A and m the slope, is:

Then for 1)
m = 2 and A(0, 0)
Next:

Then solve:

y = 2x is the answer to 1).
For 2)
m = 3 and A(1, 3)

And solve for y:

y = 3x is the answer to 2).