How do you simplify $ - 14 - 21$ ?

Hint: To solve this question, first we will discuss the steps for the addition of two negative numbers and then solve the given expression as an example of the simplest sentence by following steps. And lastly we will add both the negative numbers.

Complete step-by-step solution:
Firstly we will discuss the steps for the addition of two negative numbers:
Step-1: If both numbers are negative, we add the number together and keep the negative sign for our answer.
Step-2: If one number is positive and one number is negative we have to first find the absolute value of each number.
Step-3: Once we know the absolute value we will subtract the smaller number from the larger number.
Step-4: Our answer will have the same sign of the larger number.
Now, we will simplify the given expression:-
We can solve this expression by two ways:
First, Using directions on the number line. A negative number means we are moving to the LEFT, going DOWN the number line.
$ - 14 - 21$ can be read as:
“Go 14 to the left and then another 21 to the left”. Although this will be 35 to the LEFT, giving -35.
And, negative numbers can also be considered as debts: We have borrowed money which needs to be repaid.
Read this as “I borrowed $14$ and then another $21$ “
Although I have borrowed $35$ .
We can write this as an Addition of two negative numbers:
$( - 14) + ( - 21) = - 35$

Note: Adding positive numbers is just a simple addition. Subtracting positive numbers is just simple subtraction. Now let's see what adding and subtracting negative numbers looks like: The last two examples showed us that taking away balloons (subtracting a positive) or adding weights (adding a negative) both make the basket go down.