What are the only things that can be declared in an interface?

The width of a piece of rectangular land is 5m shorter rhan 1/3 of its length .find the width of the land if the length is 60m,150m.

Singing in the rain: this first part of the film shows the early history of motion picture. how accurate do you think the portrayal of the early motion picture industry is? why? is historical accuracy important in films and theater productions? explain.

Light travels at a speed of 186,000 miles a second. the distance light travels in a year is 5,865,690,000,000 miles/year 5,865,695,000,000 miles/year 58,656,950,000,000 miles/year 6,789,000,0000 miles/year