If 2 = 5, 4 = 18, 6 = 39, 8 = 68, then what is 10 = ?

Look for a pattern:

2 → 5
4 → 18
6 → 39
8 → 68

Check relation:

2: $2^2 + 1 = 4 + 1 = 5$
4: $4^2 + 2 = 16 + 2 = 18$
6: $6^2 + 3 = 36 + 3 = 39$
8: $8^2 + 4 = 64 + 4 = 68$

So pattern is:
$n^2 + \frac{n}{2}$

Now for 10:
$10^2 + 5 = 100 + 5 = 105$

Correct answer: 105