20 minutes is 1/3 of an hour, so an hour can be split into 3 20 minute sections.
They run 4 miles each 20 minute section equals 4 x 3 = 12 miles per hour.
To measure the exact quantity of things ;)
I Think The Answer Is 140.
The Expression: 0.8x + x = 252 Can Explain The Answer If x = 140.
Or: 1.8 Times x = 252 If x = 140.
-2-3x=3+1x
-2-3=1x+3x
-5=4x
x=-1.25
