What maximum transfer price would the calculator division accept?

If the battery division is operating at capacity (selling all of the batteries to outside customers) what minimum transfer price would the battery division accept?

If the battery division has enough excess capacity to provide the calculator division with batteries without impacting their regular demand, what minimum transfer price would the battery division accept?

Please help asap. I'll be giving positive ratings, but please only answer if you're certain of the answer. Thank you! If you could also show work that would be good.

Henderson Company manufactures electronics. The Calculator Division (an investment center) manufactures handheld calculators. The division can purchase the batteries used in the calculators from the Battery Division (another investment center) or from an outside vendor. The cost to purchase batteries from the outside vendor is $5. The transfer price to purchase from the Battery Division is $6. The Battery Division also sells to outside customers. The sales price is $6, and the variable cost is $3. The Battery Division has excess capacity