Please help!!! See image! pt. 4

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

Igure 1 and figure 2 are two congruent parallelograms drawn on a coordinate grid as shown below: 4 quadrant coordinate grid showing two parallelograms. figure 1 has vertices at negative 5, 2 and negative 3, 4 and negative 4, 7 and negative 6, 5. figure 2 has vertices at 5, negative 2 and 7, negative 4 and 6, negative 7 and 4, negative 5. which two transformations can map figure 1 onto figure 2? reflection across the y-axis, followed by reflection across x-axis reflection across the x-axis, followed by reflection across y-axis reflection across the x-axis, followed by translation 10 units right reflection across the y-axis, followed by translation 5 units down

Acircle has a radius of 12.6cm what is the exact length of an arc formed by a central angle measuring 120