Hello there need a bit of help in solving an equation to find two unknowns. the equation is

$\displaystyle P_o = \left( \frac{K_c y}{A x}\right)I_{in} + \frac{F_s z}{Ax}$

i need to find the values for x and y what i cant work out is how to isolate them and how to find 2 unknowns.

A= 5cm^2

Z= 75mm

x+y = 100mm

Kc= 2500 Newtons per Ampere

Po is in bar and is 0.2 at 4mA

Iin is in mA and is 4 at 0.2Bar

all units must be in SI

any help greatly appreciated. Thanks ian