Since we have two sides that are twice as long as the third side, we can designate each side as follows:
First side of triangle: 2x
Second side of triangle: 2x
Third side of triangle: x
Since all three sides add up to equal 60, we can set up the following equation and solve for each side:
(x) + (2x) + (2x) = 60
5x = 60 --> x = 12
Side 1 length: 2x = 2(12) = 24
Side 2 length: 2x = 2(12) = 24
Side 3 length: x = 12
I hope this helps!!