The function for question 3 is increasing because it has a positive slope.
The function for question 4 is decreasing because it has a negative slope.
How to determine if the function is increasing or decreasing?
A function will be increasing if the function has a positive slope, while a function will be decreasing if the function has a negative slope.
For question 3, the slope of the line is calculated as;
m = Δy / Δx
(x₁, y₁) = (0, 3)
(x₂, y₂) = (9, 12)
m = (12 - 3) / ( 9 - 0)
m = 9/9
m = 1
So this function is increasing.
For question 4, the slope of the line is calculated as follows;
(x₁, y₁) = (-12, 0)
(x₂, y₂) = (0, - 4)
m = Δy / Δx
m = (-4 - 0 ) / (0 - (-12))
m = (- 4) / (12)
m = -1/3
So this function is decreasing