clc
clear

a = 1.21;
b = 2.04;
c = 1.72;
d = 0.85;
f = 17.83;

x = 1 + a/b + c/f^2
s = (b-a)/(d-c)
r = 1/(1/a + 1/b + 1/c + 1/d)
y = a*b*(1/c)*(f^2/2)