Question 1065867
There are three coins left after eliminating the black/black coin. We have six sides that could be either red or black. Knowing one side is already red (as stated in the problem) then we are left with 5 sides. Of those five sides we could either have black or red. 4 out of five of those could be red as 1 out of 5 could be black. Therefore, the answer is 4/5.