Question 549875
HINT:  Two lines are perpendicular when the product of the slopes is -1.  


The slope of -4x-8y = -5 is 1/2.  The line that you are searching for must have a slope that when multiplied by 1/2 will yield -1.  So, 1/2 times what number yields -1?  How about -2?  Yes, 1/2 times -2 = -1.  The equation you need has a slope of -2.  Do you think you can find the answer now?