1)Angioplasty is a technique in which arteries partially blocked with plaque are dilated to increase blood flow. By what factor must the radius of an artery be increased in order to increase blood flow by a factor of 10?

2)When physicians diagnose arterial blockages, they quote the reduction in flow rate. If the flow rate in an artery has been reduced to 50% of its normal value due to plaque formation, and the average pressure difference has increased by 30%, by what factor has the plaque reduced the radius of the artery?

What I know is that you use Poiseuille's Law. And then you write equations for the normal and for the reduced flow rates..But then what?

Thanks