3x - 7
The perimeter is the sum of all 3 sides of the triangle
To find the third side subtract the sum of the 2 known sides from the perimeter
x + 3 + 2x + 4 = 3x + 7
third side = 6x - (3x + 7 ) = 6x - 3x - 7 = 3x - 7
10.222=10 and 222/1000
I'm not sure if that's what you were looking for but I hope this helps!
I can help with number 4 we are learning this in my class to (5th grade) Its tough
