Juno has a rectangular garden that has a perimeter of 20 ft. the width of the garden is 4 ft. what is the length of the garden?

Let P be the perimeter, l the length, and w the width.
The general formula to find the perimeter of a rectangle is P = 2(l+w). If you use the distributive property, you'll get P = 2l + 2w.
By hypothesis, we know that the perimeter is P=20 ft., and the width is w = 4 ft.
Let's use those values in the equation P = 2l + 2w
20 = 2l + 2*4
20 = 2l + 8

Now we need to solve for l. Subtract 8 from both sides to have the variable on a side and the number on the other:
20 - 8 = 2l + 8 - 8
12 = 2I
Divide both sides by 2 to get the variable alone on a side, and its value on the other side:
12/2 = (2l)/2
6 = l

So the length of the garden is 6 ft.

Let's recheck the answer (very important):
P = 2(l+w)
P = 2(6+4)
P = 2*10
P = 20 ft.
The answer has been approved.

Hope this Helps! :)