15 + 10 = 25
25 + 11 = 36
We're adding one more with each step we take.
36 + 12 = 48 <- the next number (first missing value)
48 + 13 = 61 <- this verifies that the pattern is correct
61 + 14 = 75
Similar idea with the next one:
14 + 6 = 20
20 + 8 = 28
28 + 10 = 38 <- first missing value
38 + 12 = 50 <- verifies that our rule works.
50 + 14 = 64
The one after that follows this pattern:
+7
+10
+13
+16
+19
The final one follows this pattern:
+9
+10
+11
+12
+13