Question 4546
Two lines are perpendicular if their slopes are negative reciprocals.  In your example, the given slope is -1/4. (I know that because it is the coefficient of x.)  Since the negative reciprocal of -1/4 is +4/1, or 4, the slope of the new line is 4.  So, the new line must look like this

y = 4x + ___

I can fill in the blank if I use the point you gave, (3,0).  This means that when x = 3, y = 0.  Substitute them into my equation above.

0 = 4(3) + ____
0 = 12 + ____

So, the blank must have a -12.  Therefore, the line is

y = 4x - 12.