I need a solution to these with explanations, I'm completely stuck on it

Question

The matrices below show the number of pizzas sold in each size at a local pizzeria last weekend. The cost for each size is also represented in a matrix.

Find the product of the matrices. Give the values of a, b, and c and interpret what each one represents.

Answer 1

product matrix =

|a| |$824|

|b|= |$888|

|c| |$684|

it gives the total revenue from all pizza sales

on Friday, Saturday and Sunday