Question 370581
30/(16-r)+30/(16+r)=4
30(16+r)+30(16-r)/(256-r^2)=4
480+30r+480-30r/(256-r^2)=4
960=4(256-r^2)
/4
240=256-r^2
r^2=256-240
r^2=16
Take the square root
r = 4 mph.
I think you forgot to take the square root since r^2=16
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m.ananth@hotmail.ca