Question 824849
On the number line, you represent the number {{{9}}} as the point where you land jumping {{{9}}} units to the right from zero.
You represent the number {{{12/5=2.4}}} as the point where you land jumping {{{12/5=2.4}}} units to the right from zero.
You represent adding those numbers as jumping both jumps, one after the other.
On the 3 number lines below, I represented {{{9}}} ,  {{{12/5}}} , and {{{9+12/5}}} .

{{{drawing(600,300,-30,570,-50,250,
locate(0,250,number_line(550, -2, 18, 9 )),
red(arc(175,210,250,50,-165,-15)),locate(175,235,red(9)),
blue(arc(330,110,60,50,-165,-15)),locate(325,170,blue(12/5)),
blue(line(360,114,360,130)),blue(line(360,114,345,120)),
red(line(300,214,285,230)),red(line(300,214,280,216)),
locate(0,150,number_line(550, -11, 9, 12,11,12/5 )),
locate(0,50,number_line(550, -2, 18, 9,9+12/5 ))
red(arc(175,10,250,50,-165,-15)),locate(175,35,red(9)),
red(line(300,14,285,30)),red(line(300,14,280,16)),
blue(arc(330,10,60,50,-165,-15)),locate(325,70,blue(12/5)),
blue(line(360,14,360,30)),blue(line(360,14,345,20))
)}}}