Which expression forms an equation with the given expression?

pls help

Acontractor needs 54 square feet of brick to construct a rectangular walkway. the length of the walkway is 15 feet more than the width. write an equation that could be used to determine the dimensions of the walkway. solve this equation to find the length and width, in feet, of the walkway.

The surface area of the triangular prism is .

Solve the triangle. a = 21°, c = 105°, c = 5