Answer:
x = 1
Step-by-step explanation:
Subtract 3 from both sides
x+ 3 - 3 = 4 - 3
gives x=1
A triangles measure = 180
45 + 35 + x = 180
80 + x = 180
x = 100
Hope this helps!
5.197 rounded to the nearest tenths would be 5.2
Assuming the distribution is continuous, you have

If instead the distribution is discrete, the value will depend on how the interval of number between 1 and 29 are chosen - are they integers? evenly spaced rationals? etc
X + 19 + 7x + 9 = 180
8x + 28 = 180
8x = 180 - 28
8x = 152
X = 152 : 8
X = 19