Wheat plus and minus

If the price of wheat is increased by 20% today, at what percent should it be decreased tomorrow, so as to bring down the price back to the original?

Final Answer:

p =  16.6667 %

Step-by-step explanation:

$$\begin{gathered} r_1=100\%+20\%=1+\frac{20}{100}=1.2 \\ {r}_1\cdot r_2=1 \\ {r}_2=1/r_1=1/1.2=\frac{5}{6}\doteq 0.8333 \\ {r}_2=1-p/100 \\ p=100\cdot (1-r_2)=100\cdot (1-0.8333)=16.6667\% \end{gathered}$$

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