Respuesta :

Constant! You can tell because 4 to get to 12 is multiply by 3 and the y values to those numbers work!
rate of change =change in y/change in x

if u see in the table 
choose first x,y values
y2-y1/x2-x1=rate of change

x1=0,y1=0
x2=3,y2=7.5
x3=4,y3=10
x4=9  y4=22.5

each time u will get rate of change=2.5 so it is constant