Fix: Exercise 6, 10 & 19

[codingkatty]

Hi! I've made some fixes to the solutions to exercise 6, 10 and 19 to make them more relevant to the requested code.

---

Copied from the exercise ⌨️

• Exercise 6
  • Two const variables for your first name and favorite color.
  • Two let variables for your current location and mood.

Reassign a new value to at least one of the let variables and print it one more time with console.log().

• Exercise 10
  • The output of the program should look like this:

What do you have left in yuan? 560
What do you have left in yen? 2455
What do you have left in won? 3280

105.5275

• Exercise 19
  • The output should look like the following:

Nope, it isn't  5
Nope, it isn't  9
Nope, it isn't  4
My lucky number is 10!

That's all I have, thanks :)