TV discount price

The TV fell first by 20%, then by 10%. How much did it cost after the second discount if:
A) before the first discount cost 450eur?
B) after the first discount, cost 450eur?

Final Answer:

a =  324
b =  405

Step-by-step explanation:

$$\begin{gathered} q_1=100\%-20\%=1-\frac{20}{100}=0.8 \\ {q}_2=100\%-10\%=1-\frac{10}{100}=0.9 \\ a=450\cdot q_1\cdot q_2=450\cdot 0.8\cdot 0.9=324 \end{gathered}$$

$b=450\cdot q_2=450\cdot 0.9=405$

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