Chapter 1.1, Problem 47E

(a)

To determine

To calculate: To write and solve an equation to find how much one spend on each CD

Answer to Problem 47E

The equation is $0.8x=7.6$

Explanation of Solution

Given: One spend $\$30.40$ on $4$ CDs and each CD costs the same amount and is on sale for $80\%$ of the original price

Calculation:

Let the original price of CD be $x$

Given that CD is on same for $80\%$ of the original price

Thus, amount of one CD is calculated as follows:

  $Cost=0.8x$

Also, given that one spends $\$30.40$ on $4$ CDs

Thus, cost of one CD is calculated as

  $\begin{array}{l}C=\frac{30.40}{4}\\ C=7.6\end{array}$

Thus, equation is given as

  $0.8x=7.6$

On solving the equation:

  $x=9.5$

Conclusion:

Hence the required equation is $0.8x=7.6$

(b)

To determine

To calculate: To find if person will be able to buy $3$ more CDs

Answer to Problem 47E

The person will not be able to buy three more CDs.

Explanation of Solution

Given: The next day, the CDs are no longer on sale. One have $\$25$

Calculation:

Since the CDs are not on sale.

Thus, price of each CD is $\$9.5$

Cost of three CDs is calculated as

  $\begin{array}{l}Cost=3\times \$9.5\\ Cost=\$28.5\end{array}$

Now, since the person has only $\$25$ and cost of three CDs is $\$28.5$

Thus, person is short of money

Conclusion:

Hence person will not be able to buy three more CDs.