Answer:
Let's call the length of side 1 "x". Then, the length of side 2 is 2x, and the length of side 3 is x + 4. So, the expression for the three sides of the triangle can be represented as:
x + 2x + (x + 4) = 3x + 4
This expression represents the sum of the lengths of all three sides of the triangle.
Explanation: