PolynomialReduce

PolynomialReduce[poly,{poly1,poly2,…},{x1,x2,…}] yields a list representing a reduction of poly in terms of the polyi. The list has the form {{a1,a2,…},b}, where b is minimal and a1 poly1+a2 poly2+…+b is exactly poly. 

Please visit the official Wolfram Language Reference for more details and examples on core symbols.