To find the expression that represents the perimeter of Elliot's sandbox, we need to know the lengths of the three sides of the triangular sandbox, represented by the variable \(x\) and any constant values.
The perimeter of a triangle is the sum of the lengths of all three sides. If the sides are represented as \(a\), \(b\), and \(c\), then the perimeter \(P\) is given by:
\[ P = a + b + c \]
Without more information about how \(x\) relates to the lengths of the triangle's sides, we can't determine which expression correctly describes the perimeter. However, if we assume that the sides might be expressed in terms of \(x\), then we need the specific linear dimensions represented.
If, for instance:
- The first side is \(x\)
- The second side is \(10\)
- The third side is \(2\)
The perimeter would be calculated as:
\[ P = x + 10 + (some\ other\ side\ represented\ in\ terms\ of\ x) \]
Without the explicit side length information, the choices given cannot be accurately analyzed. Generally, if we had access to specific side length relationships, we'd choose the expression accordingly.
If we are to guess based on the options, and if \(10\) and others are from some side length notation, then "3x + 10" could potentially be the right expression if each side was structured around three terms summing to \(10\).
However, I recommend checking the model or description provided for specific lengths. If you have additional information or specific lengths of those triangle sides, I can help derive the perimeter correctly.