How much power does a USB-C Digital AV Multiport Adapter supply to the USB port? (see picture)

[rodion15]

I'm charging a macbook 12inch 2013 like this (since I don't have a USB-C to USB-C cable): so I'm feeding the 14.5volts to the USB-C Digital AV Multiport Adapter (that's the voltage of the 29watt USB-C power adapter). My doubt is: what's the voltage supplied to the macbook?, is it the 14.5 volts or is the Multiport Adapter transforming the voltage from 14.5 to 5volts?
I know the macbook is charging as I can see the charging ray icon.