`{:(8,7,10,12),(13,12,15,17),(10,9,?,14):}`

Options

A. 12
B. 10
C. 21
D. 25

Answer

A

Explanation

`{:(8,7,10,12darr,+5),(13,12,15,17,),(10,9,?,14darr,-3):}`
`= ? = 15 - 3 = 12`