Got a problem here. Can someone explain how to write an equation in slope intercept form for the line that passes through the point (4,2) and is perpendicular to the graph y=1/2x+1.

since in the form y = mx + b, the slope of the line is m

so for your line y = (1/2)x + 1, the slope is 1/2

But for perpendicuar lines, their slopes are opposite reciprocals of each other, so the slope of your new line must be -2/1 or -2
and the new equation must be
y = -2x + b
with (4,2) lying on it, so
2 = -2(4) + b
10 = b

new equation: y = -2x + 10