18 and 20
18, 21, 24, 27.
-4
There are 3 feet in a yard, so 3 x 7 is 21. There are 21 feet in 3 yards, so 7 yards is greater than 18 feet.
-15.2
22
less than
The even whole numbers greater than 21 and less than 28 are: 22, 24 and 26
25
less
greater than
A deficient number is a number for which the sum of its positive integer factors (other than itself) is less than itself. The sum of the factors of 18 is 1 + 2 + 3 + 6 + 9 = 21. Since 21 is greater than 18, 18 is an abundant number.