Firstly setup an equation to find the perimeter:
3x + 4x + 5x = 54, this is because perimeter is equal to sum of all side lengths
Then combine like terms:
12x = 54
Now use the division property of equality by dividing both sides by 12:
x = 4.5
So then, you will substitute the value of x for each value of the side lengths:
3(4.5) = 13.5 for AB, 4(4.5) = 18 for BC, and 5(4.5) = 22.5 for AC.
Hope this helps and let me know if you have any more questions!
