Answer:
In a rhombus, all sides are equal. Therefore, you can set WV (s+12) and UV (3s) equal to each other.
s+12 = 3s
Subtract s from both sides, so the variables are all on one side.
12 = 2s
Divide both sides by 2 to isolate the variable.
6 = s
UV = 3s
UV = 3(6)
UV = 18