Simply the following lambda expressions, if possible. Always evaluate the "outer" applications first $($i$.$e$.,$ use lazy evaluation$).$

a$)\backslash$lambda x$.\backslash$lambda y$.($y x$)\backslash$lambda x$.\backslash$lambda y$.($x y$)$

b$)\backslash$lambda y$.($y y$)\backslash$lambda y$.($y y$)$