Final answer:
Without the correct algebraic expression, it is not possible to accurately simplify it. It seems like the student made some typographical errors in the submission. The correct expression is needed to provide help.
Step-by-step explanation:
The question seems to be asking to simplify an algebraic expression which involves variable terms with coefficients and exponents. The expression presented has some symbols that don't fit into the context, making it incomprehensible. It is important to provide the correct expression to simplify. If the expression was meant to be 6xy^3 − xy + 18xy − 6xy, then the simplification process involves combining like terms. The terms 18xy and − 6xy are like terms, and so are the terms 6xy^3 and − xy, assuming that xy refers to x times y.