Solution:
If we multiply 90 negative integers with 9 positive integers, then the sign of the product is positive.The multiplication is going to be positive when the number of negative integers within the multiplication is even. Therefore, the multiplication of 90 negative integers will yield a positive integer.
The multiplication of two or more positive sign integers has always been a positive integer. Therefore, the multiplication of 9 positive integers will yield a positive integer.
As the multiplication of two same signed integers has always been a positive integer, therefore if we multiply 90 negative integers and 9 positive integers then the sign of the product is positive.
