my domain is 1,2,3,4,5,6 and my range is 180,165,150,135,120,105, the domain is increasing by 1 and the range is decreasing by 15 but I do not know how to write the function

since the range decreases by 15 for each increase of 1 in the domain, the function will be something like

y = -15x

But, since y(1) = 180, not -15, we have to add in 195, and we get

y = -15x + 195