Answer:
or 
Step-by-step explanation:
Given

Required
Solve for x using:

First, we need to identify a, b and c
The general form of a quadratic equation is:

So, by comparison with 

Substitute these values of a, b and c in




Split the expression to two
or 
To solve further in decimal form, we have
or 
or 
or 
If we add $0.14 until we get $21.64, we would add it 154.572 times. To check this answer and make sure I’m right, do this equation: 0.14 x 154.572, then you would get 21.64.
The correct answer is 154.572 minutes.