Vancouver is a city on the north bank of the Columbia River in the U.S. state of Washington and the county seat of Clark County.
The width of the twin quilt is 66 +12 (for the two extra columns of 9 patches) + 4 (for the two extra strips of sashing) =82, which is a bit wider than your target of 78, but close enough. Plus, it's nice to have it a bit too large than a bit too small.
Description : Twin mattresses are also known as 'singles' and are the ideal choice for children bedrooms and for multi user guest rooms. Their narrow width fits most small rooms. A variation of the mattress is the Twin XL mattress which is 5 inches longer than the standard twin size but has the same width . They are commonly used in college dormitories and hostels to accommodate tall teens and are often used in bunk beds also. Dimensions : Standard twin : 39 (width) x 75 (length)