4 x 5 = 5 x 4, represents which law?
Commutative law
Associative law
Multiplicative identity
Distributive law
The cost of 3 books and 5 notebooks is Rs 250, while the cost of 4 books and 4 notebooks is Rs 280.
If the cost of a book is represented by x and the cost of a notebook is represented by y, then which set of equations represents the given information?