In the first place, the largest exponent on the independent variable (indeed the only exponent on the independent variable in this example) is 1, then this is a linear function, i.e. the graph is a straight line.
The lead coefficient is negative, so the graph will slant downward from left to right. In other words, the bigger gets, the smaller gets.
The absolute value of the lead coefficient is less than 1, hence the angle that the graph makes with the -axis will be greater than measured counterclockwise from the positive -axis.
The value of the lead coefficient is , so for every 4 units moved to the right on the horizontal, the value of the function will decrease 3 units.
There is no constant term, so when the value of the independent variable is zero, the value of the function is also zero. That is to say that the graph passes through the origin (0,0).
My calculator said it, I believe it, that settles it