First you find the price after tax. You multiply 40 times .085 add that answer (3.4) and get 43.4. After that you get the tip. You multiply 43.4 times .18 and add that answer ( 7.8) and get 51.21.
13. a) Since AC and AB are tangents to the circle, we know that two tangents that meet at an external point are equal.
Hence, AB = AC; so, AB = 40 ft.
13. b) (20 + r)² = 40² + r²
400 + 40r + r² = 1600 + r²
40r = 1200
r = 30
Hence, the diameter is 60 ft.
Answer:
A quadratic equation is of the form:
.....[1] where
a. b and c are coefficient and x is the variable.
The solutions of the equation are;

Given the function: 
To find the zero of this function.
Set f(x) = 0
⇒
On comparing this with equation [1] we have;
a = 6, b = 12 and c = -7
then;


or

or


Therefore, the zeros of the quadratic function f(x) are;
and 
Let a set of

elements.
We can find

(factorial) of the

element.
However, combination of the element lead to less than

possibilities.
(combining like adding or multiplying)
So the proposition is false.