Question

for each of the situations below, choose the action that will make the calculation work.
in each case, the units for each input and the result are given in parentheses ().
if you dont know what make a conversion factor and use a conversion factor mean in the pull-down menus, click the check answers button and read the conversion concepts lesson.
bob is planning an event and needs to purchase enough soda for all the people attending. choose the action that bob should use to do this calculation.
number of people (people)
cans of soda per person (cans/person)
cans of soda needed (cans)
a developer has a large number of acres of undeveloped land. she agrees to donate some of the acres to the county for a park in exchange for the right to build houses on the remaining land. choose the action that the developer should use to calculate the number of acres that remain for development.
donated acres (acres)
initial acres owned (acres)
remaining acres (acres)
sarah needs to do reading for both her biology and chemistry classes and wants to know how many pages of reading she has in total. choose the action that sarah should use to do this calculation.
chemistry pages to read (pgs)
biology pages to read (pgs)
total pages to read (pgs)

Explanation:

Step1: Calculate total soda cans

Let $N$ = number of people, $R$ = cans per person.
Total cans = $N \times R$

Step2: Calculate remaining acres

Let $I$ = initial acres, $D$ = donated acres.
Remaining acres = $I - D$

Step3: Calculate total reading pages

Let $C$ = chemistry pages, $B$ = biology pages.
Total pages = $C + B$

Answer:

1. Bob's calculation: Multiplication (Number of people $\times$ Cans of soda per person = Cans of soda needed)
2. Developer's calculation: Subtraction (Initial acres owned $-$ Donated acres = Remaining acres)
3. Sarah's calculation: Addition (Chemistry pages to read $+$ Biology pages to read = Total pages to read)