Answer:
y = 1/4(x) + 8 or y - 1/4(x) = b, with b's value not mattering.
Explanation:
First, convert it to a y = mx + b format. This isn't 100% necessary, just something I prefer to do.
y + 4x = 8
y = -4x + 8
Now switch the numerator and denominator of the 'm', then multiply it by -1.
y = 1/4(x) + 8
The 'b' here can be any value and still be the right answer, as slope determines whether it's perpendicular or not, not where on the y axis the line is. You may need to convert it back to the original format by subtracting the 1/4(x) and moving it to the other side, like so:
y - 1/4(x) = b