There are 12 inches (in). in 1 foot (ft). which expression can be used to find the number of inches in 2.5 feet?

Given:
12 inches in 1 foot
number of inches in 2.5 feet

2.5 feet * 12 inches/1foot = 2.5 * 12 inches = 30 inches

1 foot + 1 foot + 0.5 foot = 2.5 feet
12 inches + 12 inches + 6 inches = 30 inches

12 inches : 1 foot = x : 2.5 feet
12 inches * 2.5 feet = x*1foot
30 inches * feet = x * foot
30 inches = x

Recall that a cube has all edges the same length (See Cube definition). This means that each of the cube's six faces is a square. The total surface area is therefore six times the area of one face.