Answer:
The ans is -14 if you use desmos and start "finger counting" the slope of -3, y will equal -14 once it reaches (3,y)
Answer:

Step-by-step explanation:
To find x, the following equation is generated given the available information:



Cross multiply


Collect like terms



x+3x+3x=21
7x=21
x=3
3, 9, 9=21
the answers are 3, 9, and 9
Check whether it is possible to have a triangle with the given side lengths for example 7,9,13 then add any two sides and see if it is greater than the other side. Example the sum of 7 and 9 is 16 and 16 is greater than 13