Voltage regulator with zener diode
I feel like doing some analysis. This is a textbook type homework stuff, but if the professor went over this and you slept in class or they didn't go through this on the chalk board, I'll step you though this.

Ok, first lets look at our expected voltages, and currents then we find the current draw of each parallel branch to get the total current flow. Then we find the voltage drop across the series resistor. then add the expected voltage with the series voltage drop to get the total voltage. Now this is the maximum voltage, and this will answer your question on something like a quiz, but if you are really building this, you only apply 80% of this voltage (25.6 instead of 32V) so that there is a power safety margin.