Mandy got a $240 discount.
If you set up the equation it will be [tex] \frac{x}{1200}= \frac{20}{100} [/tex]
Now to find out what x equals you have to cross multiply. So x times 100 equals 100x. And 1200 times 20 equals 24000. 100x=24000
Divide both sides by 100 and you get x=240. So 240 is your discount.