Question

The answer & explanation !

Answer 1

Once you know how to manage percentages, exercises like this will become very easy:

computing a certain percent of a number simply means to multiply that number by a fraction with denominator 100. For example, if you want to compute the 37% of 26, you simply have to compute

`26\cdot (37)/(100)`

Let's apply this to your case: we start with an area of 250 sqft.

If we increase this area by 10%, we will have the 110% of the original area, i.e.

`250\cdot (110)/(100)`

By the same logic, after the second phase we will have the 120% of the new area, which we just computed:

`\underbrace{\underbrace{\left(250\cdot (110)/(100)\right)}_{\text{1st phase}}\cdot(120)/(100)}_{\text{2nd phase}}`

Now we can do some manipulation/semplification to get

`250\cdot(110)/(100)\cdot(120)/(100) = 250\cdot(11)/(10)\cdot(12)/(10) = 330`