It is a real number.
A real number is a combination of rational (usually negative) and irrational numbers.
A natural number is a positive integer.
But since -145 is a negative number it can't be a natural number. Making it a real number.
Correct me if I'm wrong.
You need to first add up the total cost which is 12.45, then find 6% of 12.45 which is .747 or rounded to.75.(tax) then you need to add it to get 13.20. so the tip was 13.20
ANSWER
The correct answer is option D.
EXPLANATION
The given function is

This a polynomial function. All degrees are greater than or equal to zero.
The coefficient being decimals does not disqualify it from being a polynomial.
The highest degree of this polynomial is 6.
Therefore the correct answer is D
Answer:
y intercept = 
x intercept = 
.
Step-by-step explanation:

.
y intercept





so, the answer is 
.
x intercept





so, the answer is 
.
Happy to help :)