Easiest way to work it out is to divide by ten, that gives 10% of your original number. Multiply that by two to get 20% and minus that from the original number to get the discount.
450/10 = 45 which is 10% of 450.
20% of 450= 10% x 2 or 45 x 2
therefor 20% of 450 is 90.
450-90 = the discount the shoppers recieve.
The answer is (1,-4)
Remember that the vertex is the center of the parabola.
The first problem is true because with multiplication it doesn't matter which order it is in.
The second problem is false because you will get a different quotient depending on which numbers are on which side of the equation.
