Under or Over commands
underset
$$
\dfrac{M}{p} = l(r) + \underset{+}{k(y)}
$$
Output:
underbrace
$$
Y = AD = \underbrace{C + I}_{\textrm{Private Exp.}} + \underbrace{G}_{\textrm{Public Exp.}}
$$
Output:
underset
$$
\dfrac{M}{p} = l(r) + \underset{+}{k(y)}
$$
Output:
underbrace
$$
Y = AD = \underbrace{C + I}_{\textrm{Private Exp.}} + \underbrace{G}_{\textrm{Public Exp.}}
$$
Output: