It is true, how??Here is explanation:
Consider a quadrilateral ABCD .Join diagnol AC so two triangles ABC & ACD will form.
Sum of interior angles of ABC is 180 and that of ACD is 180 as well.So, the total sum of the interior angles of ABC & ACD is 360 which is the sum of interior angles of quadrilateral itself.
Create a system of equations
x + y = 123
5x + y = 343
I use substitution
y = 123 - x
5x + 123 - x = 343
4x + 123 = 343
4x = 220
x = 55
Plug in
x + y = 123
55 + y = 123
y = 68
Check
5x + y = 343
5(55) + 68 = 343
275 + 68 = 343
343 = 343
This is simple division:

So, plug it into your calculator and you get:

Your answer's that
it takes 4.5 hrs for the surveillance run.
Answer:
Mean: 5, Median: 5, Mode: 5, Range: 4
Step-by-step explanation:
Mean: 5
5 + 4 + 6 + 3 + 7 + 5 = 30
30/6 = 5
Median: 5
3, 4, 5, 5, 6, 7,
Mode: 5
3, 4, 5, 5, 6, 7
2 fives
Range: 4
7 - 3 = 4