Answer:

Step-by-step explanation:
we have

we know that


substitute

Simplify

D. x + 4 = 7
The next step, after subtracting 1 from 8, which equals 7, is to turn your attention to the absolute value, turn everything into a positive within those lines. since x - 4, the negative subtracting the 4 should be turned positive, so it should now be x + 4 = 7.
Let X = Marinas speed in MPH
Let T = Time
T=288/X
312=(X+6)T
312=(X+6)(288/X)
312=288X/X+1728/X
312=288+1728/X
312-288=1728/X
24=1728/X
24X=1728
X=1728/24
X=72 MPH FOR MARINA
72+6=78 MPH FOR JAMIE