the answer should be C. y=-3x+7
use the formula y=mx+b where mx is the slope and b is the y-intercept.
in this case, the slope is decreasing by 3 so -3 would fit in for mx. if you look on the y-int you’ll see that the value is positive 7.
when you put this together, you’d get the equation y=-3x+7
hope this helps.