Can you work out the next letter?

O N is to A and V E is to Q as J G is to C

 

The numerical position in the alphabet of the single letter is given by the result of the first letter minus the second letter, i.e.

O = 15 N = 14; 15 - 14 = 1 = A

V = 22 E = 5; 22 - 5 = 17 = Q

J = 10 G = 7; 10 - 7 = 3 = C