🔧 Fix typo mistake

Expenses is a set of expenses and its descritption.

08_Day_Objects/08_day_objects.md

@@ -501,7 +501,7 @@ console.log(copyPerson.hasOwnProperty('score'))
 
 ### Exercises: Level 3
 
-1. Create an object literal called _personAccount_. It has _firstName, lastName, incomes, expenses_ properties and it has _totalIncome, totalExpense, accountInfo,addIncome, addExpense_ and _accountBalance_ methods. Incomes is a set of incomes and its description and expenses is a set of incomes and its description.
+1. Create an object literal called _personAccount_. It has _firstName, lastName, incomes, expenses_ properties and it has _totalIncome, totalExpense, accountInfo,addIncome, addExpense_ and _accountBalance_ methods. Incomes is a set of incomes and its description and expenses is a set of expenses and its description.
 2. **** Questions:2, 3 and 4 are based on the following two arrays:users and products ()
 
   ```js