To start, first determine the slope of the line that is perpendicular to the equation y=2x. To find it, note that the slope of a line perpendicular to another is always the negative reciprocal (or the inverse, for example the reciprocal of 3 is 1/3) which would mean that the slope for the perpendicular line would be -1/2. Then, use the slope intercept form, y=mx+b to find your remaining missing values of the equation. Because the line passes through (0,1), you can plug into the x and y values, 0 and 1, respectively, and since you know the slope is -1/2, you can plug that into m. However, the only value you must find is b, which can be solved using your three known values. When you plug the values in, you will get this equation:
1=-1/2(0)+b
Then, when you simplify and solve for b, you should get b=1.
Now that you have your b and m value, you can finally write your perpendicular equation as y=-1/2x+1
