Answer: 
<u>Step-by-step explanation:</u>
There is 1 four out of 6 possible numbers = 
Third length =
12-7 = 5
12+7 = 19
Third length can be only in this range
5Means the third length must be greater than 5 and less than 19.
Hope this helps!
Answer:
4
lolz sorry for a late answer bud
Step-by-step explanation:
This site will tell you how https://sciencing.com/write-functions-math-8315770.html
I’m not very good at explaining it sorry