The equation of a line is written as y =Mx + b, where m is the slope and b is the y intercept, which is the y value when x = 0.
You are told the slope is -1/4, so replace m with -1/4. You are also given the point (0,0) which means when x is 0, y is also 0, so replace b with 0.
The equation becomes y= -1/4x + 0
Because y is 0 you aren’t adding anything to the equation so you can remove it from the equation.
Answer is y = -1/4x