Xiao was mistake because 3(20+30) still can divide by 10. The sum is 30(2+3)
It's a rational number. 9 is a perfect square. What you have asked is written as -sqrt(9), which can be written as -sqrt(3*3) which is - 3. That's perfectly OK. What would not be OK is something like -sqrt(10) which is irrational because it cannot be represented as a fraction or a whole number or a repeating decimal or a decimal that terminates.
Answer:
Part 1) Slope-intercept form
Part 2) The slope of 2.20 tells me the rate per mile and the y-intercept of 2.50 tells me the flat fee
Step-by-step explanation:
Part 1) we know that
The linear equation in slope intercept form is equal to

where
m is the slope or unit rate
b is the y-intercept or initial value
In this problem we have

This is a linear equation in slope intercept form
where


Part 2) we have that
x -----> represent the number of miles
y ----> represent the total charge in dollars
The slope is
---> unit rate
The y-intercept is
----> initial value or flat fee
therefore
The slope of 2.20 tells me the rate per mile and the y-intercept of 2.50 tells me the flat fee
The order is: 9.036, 9.535, and 9.982.