The construction of a building requires of steel per story.

a.

Define a variable write an equation for the number of steel required if the building has 15 stories:

Let can be represents tons of steel.

There are of steel required for every story and there are stories.

So the total number of tons of steel required can be found by multiplying by .

.

Therefore, the expression of the total number of tons of steel required is .

b.

Find how many tons of steel required:

              (Orginal expression)

             (Multiply)

Therefore, the construction of a building requires total of steel.

a. The expression for the total number of tons of steel required is .

b. The construction of a building requires total of steel.