Okay, well we start out with the equation P=66, where P is perimeter. You should create equations using variables to explain each piece of information you are given. Follow the equations below and see if you can understand how to do another one like this. In this problem, l is length and w is width.
P = 66 The perimeter is equal to 66
l = 3 + w The length of one side is 3 more than the width
2l + 2w = 66 A rectangle's perimeter is calculated by adding the lengths and widths
2(3 + w) + 2w = 66 Use what you know about length from step 2 to replace the variable in step 3
6 + 2w + 2w = 66 Multiply
6 + 4w = 66 Add like terms
4w = 60 Subtract
w = 15 Divide
l = 3 + w Remember step 2?
l = 3 + 15 Replace the variable using your value for w
l = 18 Add
And you're done! Always check your work. It helps to create a picture of a rectangle while you're doing these problems as well. As you get used to these problems more and more, you can show more or less work than I've shown, but try to stay true to what the teacher asks of you. Good luck!
