Answer:Obtain a systematic sample by selecting every 20th vehicle that passes (in any lane and going in any direction).
Step-by-step explanation:
To solve problems like this you can either graph or solve mathematically. To do the ladder we need to solve for one variable at a time. So lets cancel one variable out.
Multiply equation 1 by 2
This will give 4x-2y=14
Now we can get rid of y by subtracting 2 from 1
This will give x=9
Plug back in to either equation, i will use equation 2
3(9)-2y=5 simplify
-2y=-22 solve
Y=11
5 · (6 - 1) + 3
= 5·5 + 3
= 25 + 3
= 28
It would use 2.83 gallons of gas for a 2 hour trip