Write the set {14,21,28,35,42,98} in the set-builder form

To solve this problem you must apply the proccedure shown below: 
 1. You have the following set {14,21,28,35,42...98}.
 2. As you can see, the numbers are multiples of 7 and they are greater than 7 and less than 100. 
 3. Therefore, you can write the set, which we will call Z, in the set-builder form as following: 
 Z={x:x ∈ N, x is multiple of 7 greater than 7 and less than 100}
 The answer is: Z={x:x ∈ N, x is multiple of 7 greater than 7 and less than 100}