The perimeter of a rectangle is 20 cm. the length is 7 cm. what is the area?

Hey there!

So we know the perimeter is 20 cm. Let's make our formula for this.

2L + 2W = 20

The formula for the area of a rectangle is L x W. Let's make this into our formula and fill it in as time goes.

L x W

Our Length is measured at 7 cm, so let's fill that into our formulas.

2(7) + 2W = 20
7 * W = x

Let's use some basic algebra to solve for our perimeter.
2(7) + 2W = 20
14 + 2W = 20
2W = 6
W = 3

This means our Width is 3. Now all we have to do is solve for our area since we have our dimensions.

7 x 3 = 21

The area of the rectangle is 21 cm^2.

I  hope this helps!

First, think of what you know. you know that the number t the end of the equation will need to be subtracted because it is the money he lost from buying the lawn mower. and your first two weeks have negative profit, so that tells you that c and d are wrong. now you can plug any of the weeks into a and b to see which one works. i'll start with plugging week 1 into a.this isn't right because it says your answer for week one should be -90.so now we need to try the same thing with b.this one got you the right answer, (sometimes if you only check with one of the weeks multiple will work so you need to check with more of the weeks, but it worked out fine here)this means that b is the correct answer.let me know if you need more clarification. i hope this : )