Hello there! :)
We are given that the line passes through the point (4,5) and that it's perpendicular to the line y=2x-3.
Perpendicular lines have slopes that are opposite reciprocals.
This means we take a number, make it negative, and flop it over:
2
-2
-1/2
So the slope of the line perpendicular to y=2x-3 is -1/2.
Now, we have the slope and a point that the line passes through, so we can write the equation in point-slope form, which looks like so:
y-y1=m(x-x1)
Where
y1 is the y-coordinate of the point
m is the slope
x1 is the x-coordinate of the point
Now, let's plug our values into the equation:
y-y1=m(x-x1)
y-5=-1/2(x-4)
y-5=-1/2x+2
y=-1/2x+2+5
y=-1/2x+7
Hence, that is the equation of the line.
Hope it helps.
~A lonely teen who helps others with a smile
-Grace :-)
Good luck.