why am I getting the error Incorrect Number or Types of Inputs or Outputs for Function

For equality inside a symbolic expression, use double equal signs (==) —

syms d e 
s=solve(7*d + 3*e == 71,d + 2*e == 20);
s=[s.d s.e];
disp('1 dollar = ');

1 dollar = 

vpa(s(1),3)

ans = 7.45

disp('Eullar');

Eullar

The ability to use character arrays has been removed (depricated). Although ‘e’ was not included in the syms call, I assume it is a variable and not the exponential function e that is the exp function. If it should be ‘exp(1)’ (or the exponential function of some other argument), make the appropriate changes in your code.