display deposit amout in booking form


My plugin is set up with the deposit features, I would like to display the amount of deposit for the price selected on the appointment form.

Like that:
Date and time: 11th March 2015 8:00 am
Lasts (approx): 60 minutes
Price: 70 GBP (17.50 GBP deposit)

(the amount of deposit is not displayed anymore on the button since my confirm button redirect to Paypal)

How can I do that?

Best regards,