A waiter had 41 customers. After some more arrived he had 43 customers. How many new customers arrived?
The waiter had 41 customers. 
Then, some more arrived. 
That means that the number of customers increased by some amount. 
Now we have 43 customers. 

We can set up an equation to solve this problem: 

41 + x = 43 

We can solve for x by subtracting 41 from both sides: 

41 + x = 43 
41 + x - 41 = 43 - 41 
x = 2 

So, 2 new customers arrived.