Is there a restriction that the set must be positive? or whole numbers? Because negative numbers can be even, which makes your set an infinite list of numbers.
Natural numbers: P = {2, 4, 6, 8, 10}
Whole numbers: P = {0, 2, 4, 6, 8, 10}
All real numbers: P = {2n ;n ≤ 5}
I can see it, it's too blurry and small
just like the previous one, we sum the sides to get the perimeter.

0.3*42 this gives you a 30% discount
3/10*42 this gives you a 30% discount
0.03*42 this gives you a 3% discount
3 *4.2 This is not a discount