6. The steps your friend took to divide two mixed numbers are shown. \[ \begin{aligned} 3 \frac{3}{5} \div 1 \frac{1}{2} & =\frac{18}{5} \times \frac{3}{2} \\ & =\frac{27}{5} \\ & =5 \frac{2}{5} \end{aligned} \] What should your friend change in order to divide the two mixed numbers correctly? A. Find a common denominator of 5 and 2. B. Multiply by the reciprocal of \( \frac{18}{5} \). C. Multiply by the reciprocal of \( \frac{3}{2} \). D. Rename \( 3 \frac{3}{5} \) as \( 2 \frac{8}{5} \). 7. A company ordering parts receives a charge of \( \$ 25 \) for shipping and handling plus \( \$ 20 \) per part. Which equation represents the cost \( c \) (in dollars) of ordering \( p \) parts? F. \( c=25+20 p \) G. \( c=20+25 p \) H. \( p=25+20 c \) I. \( p=20+25 c \)

Your friend should recognize that to divide mixed numbers, the correct approach involves converting the mixed numbers into improper fractions. After converting \( 3 \frac{3}{5} \) as \( \frac{18}{5} \) and \( 1 \frac{1}{2} \) as \( \frac{3}{2} \), the next step is indeed to multiply by the reciprocal. This means using option B, which states that they should multiply by the reciprocal of \( \frac{3}{2} \) to ensure the division is done correctly! Now, regarding the company's cost equation, option F is the correct representation: \( c = 25 + 20p \). Here, the company charges a flat rate of \( \$ 25 \) for shipping and handling, and then adds \( \$ 20 \) for each part ordered, making it easy to calculate your total cost as you ramp up your parts order. So, always keep an eye out for those fixed costs!