To solve this problem, we need to first find the dimensions of the side of the blue and purple squares.
We're given that the purple (smaller) square has a side length of x inches.
We are also given that the blue band has a width of 5 inches.
Since the blue band surrounds the purple square on both sides, the length of the blue square is x+2(5)=x+10 inches.
The net area of the band is therefore the difference of the area of the blue square and the purple square, namely take out the area of the purple square from the blue.
Therefore
Area of band

[recall



or 20(x+5) if you wish.
The missing fraction would be

since it is exactly in the halfway between
f(x)=10x to the power of two +4
So first, find out the total amount of money you make in 3 months.
If you make 1200 dollars a month, then in 3 months, you can make 3600 dollars. This is because 1 month salary + 1 month salary + 1 month salary = 3 month salary, and 1 month salary = 1200. So 1200 + 1200 + 1200 = 3600.
Since you're saving 2/5 of that, the simplest method to do this is to divide by 5, to find 1/5 of 3600, then multiply by 2 to find 2/5.
3600/5 = 720
720 * 2 = 1440
So you can save $1440 in three months.