Index numbers application

I can calculate indices and do simple problems like “if index is 102 and the price was 20, what will be the price of index is 140”. But certain applications i simply can not understand. here is an example:
Month-Prod—OH———Price
———Units—Costs—–Index
Jan 10——-3352——-100
feb 10.5—–3479——-101
mar 12——-3860——-102
apr 9———3098——-104
may 9.5——3225——-105
jun 10.25—3416——-106

question: Use the hi-lo method o calculate the cost per unit in June’s prices

the hi is march and lo is april. is the question asking to adjust costs to june index? how do we do it?

regards