The y-intercept is the value where the line crosses the y-axis. This occurs when x = 0. So, to calculate the y-intercept, we substitute x = 0 into the function.
The function is: f (x) = -1.25x +7
So, when x=0, the function becomes: f(0) = -1.25*0 + 7 = 7
Therefore, the y-intercept is 7.