Two friends were betting. One said to the other, “The coin will be flipped twenty times and each time the coin lands on head, I will give you $2 and each time it lands on tale, you will give me $3.” After flipping the coin for twenty times not a single penny was exchanged among them.

How many times did the coin land on heads ?

12

Let x be the number of time heads appeared

2x = 3(20-x) --- this is because the amount won and lost was equal

X=12