In a certain coding language, if the word 'DRIVE' is coded as 'GOLSH', then the word 'COINS' will be coded as:

Applying the alternating shift to COINS gives FLLKV.

In DRIVE to GOLSH the letters move by plus three, minus three, plus three, minus three, plus three.

So the first letter goes forward three, C becoming F, and the second back three, O becoming L.

The third goes forward three, I becoming L, and the fourth back three, N becoming K.

The fifth goes forward three, S becoming V, giving FLLKV.