[Currency Exchange]: Reworded task explanations

exercises/concept/currency-exchange/.docs/instructions.md

@@ -7,12 +7,11 @@ Your friend Chandler plans to visit exotic countries all around the world. Sadly
 Create the `exchange_money()` function, taking 2 parameters:
 
 1. `budget` : The amount of money you are planning to exchange.
-2. `exchange_rate` : Unit value of the foreign currency.
+2. `exchange_rate` : The amount of domestic currency equal to one unit of foreign currency.
 
 This function should return the value of the exchanged currency.
 
 **Note:** If your currency is USD and you want to exchange USD for EUR with an exchange rate of `1.20`, then `1.20 USD == 1 EUR`.
-
 ```python
 >>> exchange_money(127.5, 1.2)
 106.25
@@ -39,7 +38,10 @@ Create the `get_value_of_bills()` function, taking 2 parameters:
 1. `denomination` : The value of a single bill.
 2. `number_of_bills` : Amount of bills you received.
 
-This function should return the total value of the given *bills*.
+This exchanging booth only deals in cash of certain increments. 
+The total you receive must be divisible by the value of one "bill" or unit, which can leave behind a fraction or remainder.
+Your function should return only the total value of the bills (_excluding fractional amounts_) the booth would give back.
+Unfortunately, the booth gets to keep the remainder/change as an added bonus. 
 
 ```python
 >>> get_value_of_bills(5, 128)
@@ -50,8 +52,10 @@ This function should return the total value of the given *bills*.
 
 Create the `get_number_of_bills()` function, taking `budget` and `denomination`.
 
-This function should return the *number of bills* that you can get using the *budget*.
-**Note: ** You can only receive _whole bills_, not fractions of bills,  so remember to divide accordingly.
+This function should return the _number of new currency bills_ that you can receive within the given _budget_. 
+In other words:  How many _whole bills_ of new currency fit into the amount of old currency you have in your budget? 
+Remember -- you can only receive _whole bills_, not fractions of bills, so remember to divide accordingly. 
+Effectively, you are rounding _down_ to the nearest whole bill/denomination.
 ```python
 >>> get_number_of_bills(127.5, 5)
 25
@@ -61,8 +65,9 @@ This function should return the *number of bills* that you can get using the *bu
 
 Create the `exchangeable_value()` function, taking `budget`, `exchange_rate`, `spread`, and `denomination`.
 
-Parameter `spread` is the *percentage taken* as an exchange fee.
-If `1.00 EUR == 1.20 USD` and the *spread* is `10`, the actual exchange will be: `1.00 EUR == 1.32 USD`.
+Parameter `spread` is the *percentage taken* as an exchange fee, written as an integer. 
+It needs to be converted to decimal by dividing it by 100. 
+If `1.00 EUR == 1.20 USD` and the *spread* is `10`, the actual exchange rate will be: `1.00 EUR == 1.32 USD` because 10% of 1.20 is 0.12, and this additional fee is added to the exchange.
 
 This function should return the maximum value of the new currency after calculating the *exchange rate* plus the *spread*.
 Remember that the currency *denomination* is a whole number, and cannot be sub-divided.
@@ -81,6 +86,9 @@ Remember that the currency *denomination* is a whole number, and cannot be sub-d
 Create the `non_exchangeable_value()` function, taking `budget`, `exchange_rate`, `spread`, and `denomination`.
 
 This function should return the value that is *not* exchangeable due to the *denomination* of the bills.
+Remember - this booth gets to keep the change _in addition_ to charging an exchange fee.
+Start by calculating the value you would receive if you were able to keep subdivided bills, then subtract the amount you would receive in whole bills. 
+Both amounts should take the spread, or the exchange fee into account.
 
 **Note:** Returned value should be `int` type.