Question

The numbers on the both side of ':' have a relation
between them. If pair of numbers on both side of '::'
follow the same relation, then the number which
replace the ? is
354 : 4 :: 852 : 11 :: 794 : 12 :: 951 : ?
(1) 15 (2) 13
(3) 12 (4) 10

Answer 1

3+5-4=4
8+5-2=11
7+9-4=12
9+5-1=13