Answer:
10 is the unit rate per 1
Step-by-step explanation:
if you do a number line
and you put
10 20 30 40 50 60 70 80 90
_____________________________________________________
1 2 3 4 5 6 7 8 9
you can see that if you divide 20 by 2, you get the unit rate as 10 per 1
Hope this helps!