What would a matrix look like to calculate the price with the 7% sales tax included?

Answer:
see attached
Step-by-step explanation:
You want to multiply each individual value in the matrix by the same scalar value. That is represented as the product of a constant and the matrix.
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The tax amount on price P is 0.07P. When that is added to P so you have the price + tax, you get P + .07P = 1.07P.
In this case, P is a matrix of prices.