Answer:
10/3
Step-by-step explanation:
Given properties of the rectangle:
- The length is twice the width ( So we can say l = 2w )
- The perimeter is 20cm
Given this we want to find the width of the perimeter.
Creating a system of equation:
First off we know that perimeter = 2L + 2W
We also know that the perimeter of this rectangle is 20 cm
So we can say that 20 = 2L + 2W
We also know that the length of this rectangle is twice the width or in other words l = 2w
So we have the two equations, 20 = 2l + 2w and l = 2w
Solving the system:
We are going to use the substitution method to solve this system.
The substitution method works when you have two equations, one can be just a plain equation but the other must have one of the variables defined ( by itself on either side of the equal sign )
If you have one of the variables defined, you can plug it in ( substitute ) into the other equation and solve for the other variable.
Plugging in the defined variable into the other equation
Equation : 20 = 2l + 2w
Defined variable : l = 2w
==> plug in l = 2w
20 = 2(2w) + 2w ( now we solve )
==> multiply 2 and 2w
20 = 4w + 2w
==> combine like terms
20 = 6w
==> divide both sides by 6
20/6 = w
==> simplify fraction
10/3 = w
The width = 10/3
Checking our work:
First we must solve for length as well
<em>Solving for length by plugging in width into either equation</em>
l = 2w
==> plug in w = 10/3
l = 2(10/3)
==> multiply 2 and 10/3
l = 20/3
Now to check our we we plug in the length and width into both equations, if both are true then our answer is correct
Equation 1 : 2l + 2w = 20
==> plug in l = 20/3 and w = 10/3
2(20/3) + 2(10/3) = 20
==> simplify multiplication
40/3 + 20/3 = 20
==> add fractions
20 = 20
<em />
Equation 2 : l = 2w
==> plug in l = 20/3 and w = 10/3
20/3 = 2(10/3)
==> multiply 2 and 10/3
20/3 = 20/3
Both are correct so our final answer is correct as well! :)
