U(h)$$
% 
% These three equations could be from a model where:
%% 
% * $h$ is the number of hours an individual works
% * $y$ is the income that the individual makes as a function of work hours
% * $l$ is the number of leisure hours remaining as a function work hours
% * $u$ is the overall level of utility as a function of work hours.
%% 
% Or you might potentially want to use superscripts:
% 
% $$y = f^y(h), l = f^l(h), u = f^w(h)$$
% 
% Or we could use the same letter (small cap) for function as the lette