Which expression could be used to solve this problem? bart practices piano every day. first he practices songs for 20 minutes. then he practices scales for 15 minutes. how much time does bart practice piano in 3 days? a. 3 × (20 – 15) b. 20 × (15 + 3) c. 3 × (20 + 15) d. 20 × (15 – 3)

The answer would be C since he practices for a total of 35 or 20+15 minutes for 3 days

I would tell Eddie that he is correct if the coin is a fair coin (not weighted to favor one side).  Since coins have two sides, heads and tails, the probability of getting heads is 1 out of 2 or 1/2.  Same for tails (1 out of 2 or 1/2)
Since 325 is half of 650   (325/650 = 1/2) we know that the probability of getting heads in 650 flips is 1/2 or 325

In reality we might expect it not to be exactly 325 heads - could be 321 or 329 or even 338.   But we would not expect 35 heads and 615 tails.