I cannot work out part B

Ahomeowner plans to hang wallpaper on one wall of a bedroom that is 10 feet long if a stripe of wallpaper is 20 inches wide and stripes or hung vertically how many stripes on wall paper with the homeowner required

Henry is an avid reader, he devours 90 pages in half an hour how many pages has henry read per minute?

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36