The merchant (24) at the candy store has a difficult time with this. That’s because before fractions came to live in Numbertown all transactions were done only with dollar bills. For example, if the clothier charged $25 for a shirt or blouse and a customer paid with 3 ten dollar bills, then the merchant knew to subtract 25 from 30 and give the customer $5 in change. That’s just the way it was done. But now all that has become more complicated.

4/6 speaks to Mayor 1: "Let me tell you a story. One day I came into this store to buy the $1/5 chocolate bar. but all I had with me was $1/4. The merchant scratched its head and said angrily,  "What kind of nonsense is this? You don’t have enough money!”

"What do you mean?" asked 4/6. "Not only is $1/4 enough, but I also get change."

The merchant was dumbfounded. "You what? That's not possible,"
said 24.
 
“Let me show you,” said Mayor 1. “You know that I can take on different forms. Well, money can take on different forms as well. And each new form has the same value. For example, $1/4 can become $2/8, $3/12, $4/16 and $5/20."
 
“That should be enough," said 4/6. "Now let’s look at the different forms the price of the candy can take. The price $1/5 can also be $2/10, $3/15 and $4/20. Lets see which forms we can compare."
 
Notice that 4/6 stopped the price forms when the denominators were the same.
 
"Now do you see that I have enough money?" continued 4/6.