Answer:
9
Step-by-step explanation:
im bad at explaining
2x-7y=18 _(1)
-2x+4y=5
11y=23 , Y=23/11 sub in 1
2x-7×23/11=18
2x = 18×11 + 7×23
x = ( 198 + 161 )/2 = 359/2
ANSWER: The length of the entire dash is 700 meters.
EXPLANATION:
Because 20% of the dash equals 140 meters, we can use a variable to figure out the length of the entire dash.
Let x be the length of the entire dash.

The length of the entire dash is 700 meters.
The value could be rewritten as 2(x+4)