The formula to calculate the compound interest is:
[tex]\begin{gathered} A=P(1+\frac{r}{n})^{nt} \\ \text{ Where } \\ A\text{ is the total amount at the end of t years.} \\ P\text{ is the initial amount deposited.} \\ r\text{ is the interest rate.} \\ t\text{ is the time.} \end{gathered}[/tex]From the word problem, we have:
[tex]\begin{gathered} A=40,000 \\ P=? \\ r=7\%=\frac{7}{100}=0.07 \\ n=1\Rightarrow\text{ It was compounded once in a year.} \\ t=6 \end{gathered}[/tex]Then, we can replace the above values in the compound interest formula and solve for P.
[tex]\begin{gathered} A=P(1+\frac{r}{n})^{nt} \\ 40,000=P(1+\frac{0.07}{1})^{(1)(6)} \\ 40,000=P(1+0.07)^6 \\ 40,000=P(1.07)^6 \\ \text{ Divide by }1.07^6\text{ from both sides} \\ \frac{40,000}{1.07^6}=\frac{P(1.07)^6}{1.07^6} \\ 26,653.69\approx P \\ \text{ The symbol is read 'approximately'.} \end{gathered}[/tex]AnswerYou should deposit today $26,653.69.