Answer:
the answer is 2.90
Step-by-step explanation:
Picture a rectangle, if one side is 3.4 then the other side 3.4. Add those two togerther gives you 6.8. Now you can subtract 6.8 from the perimeter which is 12.6 then that gives you 5.8. Then you split the 5.8 which give you 2.90 which is the length of the rectangle. So if you label all the sides of the rectangle like this 3.4 + 3.4 + 2.90 + 2.90 = 12.6
