Step-by-step explanation:
Only 1 number works. 1 will make 819 which is divisible by 9.
Since it is 1 of ten numbers can go in the blank, the answer is 1/10 which is 0.1
The 10 number choices are
0,1,2,3,4,5,6,7,8,9
The only one that works is 1 as I've stated.
You have a fixed rate of $25, meaning you get a haircut, it's $25
ANY other service is an extra $15
So, let's make the equation...
y=15x+25
Now, to just get a haircut it's $25.
But, let's say you get a haircut+shampoo
It'd be..
y=15(1)+25
y=$40
Another one..
You get a haircut+shampoo+highlight
y=15(3)+25
y=$70
