Im trying to figure out how to find the length of an equilateral triangle

All 3 sides of an equilateral triangle are the same.

Set up an equation with two sides equaling each other and solve for n:

2n +15/4 = 7n

Subtract 2n from both sides:

15/4 = 5n

Divide both sides by 5:

n = (15/4) / 5

n = 3/4

Now you have a value for n, replace n and solve for the length:

7n = 7(3/4) = 21/4 = 5 1/4

Each side is 5 1/4

c) 21.5

Step-by-step explanation:

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