A boat travels 400 kilometers in 9.6 hours (with a constant speed). How much time will it take to travel 138 kilometers? (round to the nearest tenth of an hour)

What is the value of x? enter your answer in the box. (cm)

Math i have no idea how to do a and b

The pyraminx is a rubik's cube-type toy in the shape of a tetrahedron. the pyraminx shown below has edges 15\,\text{cm}15cm long and vertical height h=12.2\,\text{cm}h=12.2cm. the triangle drawn with dashed lines is a right triangle. what is the distance rr? round your answer to the nearest tenth.