Associative law multiplication

In a warehouse, you obtain a 20% discount but you must pay a 15% sales tax. Which would you prefer to have calculated first: discount or tax? Explain. (result write as: 1 = first discount, 2 = first tax, 3 = no matter what first)

Correct result:

x =  3

Solution:

$$\begin{gathered} p=1000 \\ {a}_1=p\cdot (1-20\mathrm{/}100)\cdot (1+15\mathrm{/}100)=1000\cdot (1-20\mathrm{/}100)\cdot (1+15\mathrm{/}100)=920 \\ {a}_2=p\cdot (1+15\mathrm{/}100)\cdot (1-20\mathrm{/}100)=1000\cdot (1+15\mathrm{/}100)\cdot (1-20\mathrm{/}100)=920 \\ {a}_1=a_2 \\ x=3 \end{gathered}$$

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Math student

(2 - 3)4(4) - 9 ÷ 3

1 year ago  Like

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