A rectangular poster measures 42 inches by 26 inches. A frame shop fitted the poster with a half inch mat border

To find the dimensions of the mat border, we need to subtract the dimensions of the poster from the overall dimensions of the frame.

The overall dimensions of the framed poster can be found by adding twice the width of the mat border to each dimension of the poster.

Let's start with the width:
Overall width = poster width + 2 × mat border width
= 42 inches + 2 × 0.5 inches
= 42 inches + 1 inch
= 43 inches

Now let's find the height:
Overall height = poster height + 2 × mat border height
= 26 inches + 2 × 0.5 inches
= 26 inches + 1 inch
= 27 inches

So, the framed poster will have dimensions of 43 inches by 27 inches.

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