Total Pressure Loss is the sum of friction loss and elevation change. The elevation change is usually in feet or meters. If it is feet, the conversion to PSI is 2.31 feet equals 1 PSI.
There are a couple of formulas that use diameter and length of pipe, along with flow rate to calculate friction loss in a pipe. The trick is finding the right friction coefficient/constant for the pipe material for the equation you are using. There a several on-line websites that help you calculate the friction loss. It is important to look over the explanation of the formulas so that if you use one of the sites calculators, you have an idea what is going on with it.
The first formula is The Darcy-Weisbach formula.
The other that is less accurate is Hazen-Williams Equation.
Each of these formulas have tables of piping material and the appropriate friction constant.
If you Google Friction loss in a fire hose. you find there is a calculator.
Fire Hose Friction Loss Calculator I am not sure which formula it uses. If this is a homework assignment, using this calculator may not get you the credit you want.