By making an equation, we can solve this problem.
First, we need to establish our variable. Let's call our unknown integer "x"
So, 2 times an integer can be represented by 2x So, that is (means equal to) 5 less than 21.
5 Less than 21 is 21-5.
So,
2x = 21-5
Now, just solve the equation for x.
2x = 16
x = 8
The integer you described is 8.
Hope this helps!