Baker made 8 cakes. He sold 9 of them and bought 30 new cakes. How many more cakes did baker buy than those he sold?
1. Baker made 8 cakes. 
2. He sold 9 of them. 
3. He bought 30 new cakes. 

We want to know how many more cakes did baker buy than those he sold. 

Step 1: We start with what we know. We know that baker made 8 cakes. 
Step 2: We know that he sold 9 of them. 
Step 3: We want to know how many more cakes did baker buy than those he sold. 

In order to find out how many more cakes did baker buy than those he sold, we need to subtract the number of cakes he sold from the number of cakes he bought. 

30 - 9 = 21 

Baker bought 21 more cakes than those he sold.