Answer:
30:15 (simplified is 2:1)
Explanation:
Out of the 45 times Eric flipped a coin, 30 of them landed on heads. Tails is the the only other probable occurance, so since we know that there are 15 trials left, this means that the coin landed on tails 15 times. This would give a heads to tails ratio of 30:15, but the simplified ratio would be 2:1, because that's the smallest it can be divided evenly.
45-30=15
30:15=2:1