Answer:
Hey boss man, just add up all the sides! For example, just add 3.9+3.9+3.9! and if there is a line in the middle of a certain side, it means that it is congruent or the same as another side with a dash. For example, with number 2, the side without a measurement is congruent with the the side with measurement of 7mm! Hope this helps! You got this! :)
Explanation: