Answer 1

Here is how you do matrix multiplication:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.m.wikipedia.org/wiki/Matrix_multiplication&ved=2ahUKEwjx3uW-_Jz2AhVXFrkGHUrJA6gQFnoECCEQAQ&sqi=2&usg=AOvVaw0uOWhoYCTXABEqteqWXd-4