Try this option:
the final price of the first machine after discount is:
(1-0.3)*495=346.5$;
the final price of the second machine after all the discount is:
(1-(0.2+0.2*0.1))*495=386.1$.
Short explanation: the additional 10% off is 2% of the initial price for the second machine; the final discount of the second machine is 22%.