a. The machine is $720 at 10% off. So, to find the discount, we multiply $720 by 10%. 10% = 0.1, so 720*0.1=72. Answer: 72
b. But that's not the actual price! The machine is 10% OFF. That means it is 100% of the price, $720, MINUS 10%, $72. 720-72=648. Answer: 648