Write an equation of the line passing through the point a(6,−1)a(6,−1) that is perpendicular to the line y = −2x+8y = −2x+8.

So the equation has to pass through (6,-1) and be perpendicular to y = -2x + 8.
The slope is -2, and to get the slope of a line perpendicular to another line you have to find the negative reciprocal of that slope. That means -2 is equal to 
-2/1, and if you flip those numbers and find the opposite of that number making it positive, the slope of a line perpendicular to it is 1/2.
But the line also has to pass through (6,-1), so we have to find the y-intercept of the new line.
To do that, you multiply 6(the x) by the 1/2(the slope) and get 3. Then you subtract 3(previous answer) from -1(the y) and get -4. That means the y-intercept is -4!
All that's left is to build the equation with this information. The equation is: 
y = -4 + 1/2x 
Hope this helps!

The answer would be a