Mark is installing a mosaic tile backsplash and the shape of the tiles are shaped like regular octagons. Each tile has a length from side to side of in. Once Mark gets a few pieces on the wall, he realized that there is a gap that the tiles do not cover. What size tile must he get to fill the gaps?

19

step-by-step explanation:

in the attachment.   i didn't see your choices.   the word which means there is choices.

step-by-step explanation:

(x,y)

x tells you how much left or right you go from the origin

y tells you how much down or up you go from the origin

so for example (-3,2), you go left 3 and up twice. i denoted which of the ordered pairs is which in my graph.