Answer:
39
Explanation:
Alll the sides equal each other because of that curve u see at each angle, that curve means that the angles are the same, having the same angles means same sides, so just pick two equations to do this:
21 - x = 2x -3
add 3 to both sides
24 - x = 2x
add x to both sides
24 = 3x
divide by 3
8 = x
Now input 7 into the equations:
21 - x = 21 - 8 = 13
2(8) - 3 = 16 - 3 = 13
x + 5 = 8 + 5 = 13
Now add: 13 + 13 + 13 = 26 + 13 = 39
Another way for u to save time is remember how i said all the sides were the same? you could just solve one equation, so it'll be 13 and multiply that with 3 to get the perimeter since ur adding 13 three times anyway
So just a simple: 13(3) = 39