What does an equal sign with a line across it mean?

Convert 16 yards to feet use the conversion rate 3 feet = 1 yard

What is the maximum total area that 450cm of string can enclose if it is used to form perimeters of two adjoining rectangles as shown?

The base of a triangle exceeds the height by 9 inches. if the area is 180 square inches, find the length of the base and the height of the triangle.