Write the equation in slope intercept form with a slope of - 3 and passes through (1,4)

Y = mx + b, where m = slope, and b = y-intercept.

Since you are not given the y-intercept, you have to solve for it through the equation, y = - 3x (which is the slope you are given) + b, and replace x and y with values given, which are (1,4)

y = - 3x + b

4 = - 3 (1) + b

4 = - 3 + b

7 = b

Then replace b in the first equation to get the answer

y = - 3x + 7