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}
16*8=128
12*12=144
128
+ 144
$272
Lee sold 16 hats
Not 100% but all real number so D