Please help with the tennis court one.

We have two sides of length 'w'. They are the vertical sides.

We also have two sides of length '2w+6' which are the horizontal sides.

So we have these four sides
side1 = w
side2 = 2w+6
side3 = w
side4 = 2w+6

Let's add up those four sides to get
Perimeter = (side1)+(side2)+(side3)+(side4)
Perimeter = (w)+(2w+6)+(w)+(2w+6)
Perimeter = w+2w+6+w+2w+6
Perimeter = 6w+12

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Since the perimeter is given to be 228, and we found the perimeter expression to be 6w+12, this must mean that the two are equal

So, 6w+12 = 228

Let's solve for w

6w+12 = 228
6w+12-12 = 228-12
6w = 216
6w/6 = 216/6
w = 36

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Now that we know that w = 36, we can find the dimensions of this rectangle

The vertical sides are simply w, so the vertical sides are 36 feet each. I simply replaced w with 36.

The horizontal sides are a bit more complicated. The expression we have is 2w+6 or 2*w+6. Let's replace w with 36 and use PEMDAS to evaluate

2*w+6 = 2*36+6 = 78

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Answers are...
Length = 78 feet
Width = 36 feet
(the length is the horizontal component, the width is the vertical)