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);

disp(x)
disp(s)
disp(r)
disp(y)