Solve C=AB+D for B please help I need to pass this class

Katlyn made 4 dresses with 7 yards of fabric. how many yards did she use on 1 dress?

What percent of 18 is 24? and plz explain thx.

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.