Math Question please help

ANSWER
B. y=8x +1200
EXPLANATION
If the family's well pumps on average 8 gallons of water per minute, then the unit rate of change is 8.
This implies that, the slope of the linear equation that models this situation is
[tex]m = 8[/tex]
It was also given that, the well's tank had 1200 gallons of water in the morning.
This implies that the y-intercept of the straight line is
[tex]b = 1200[/tex]
The equation is given by:
[tex]y = mx + b[/tex]
We substitute the values to obtain:
[tex]y = 8x + 1200[/tex]
The amount of water in the tank, y after it has been pumping for x minutes is
[tex]y = 8x + 1200[/tex]