Question 415000
6a^(3)h+13a^(2)h-4a^(h)-15by^(2)a^(h)+3

Arrange the variables alphabetically within the expression -15by^(2)a^(h).  This is the standard way of writing an expression.
6a^(3)h+13a^(2)h-4a^(h)-15a^(h)by^(2)+3