If the product of two matrices is AB=1/-3/5 over 2/5/7, what are the dimensions of Matrix B if A is a 2x3 matrix?

Answer:
Matrix multiplication is associative: ( A B ) C = A ( B C ) \displaystyle \left(AB\right)C=A\left(BC\right) (AB)C=A(BC).
Matrix multiplication is distributive: C(A+B)=CA+CB,(A+B)C=AC+BC. C ( A + B ) = C A + C B , ( A + B ) C = A C +