A recipe calls for 3 cups of flour to make 2 batches of dinner rolls. One batch makes 15 rolls. Laura is making dinner for 12 people and only needs one roll per person. What proportion will help Laura find how much flour is needed to make 12 dinner rolls?
A. 3/30 = x/12
B. 3/2 = x/12
C. 3/15 = x/12
D. 12/15 = x/3

A

Step-by-step explanation:

3 cups of flour produces 2 batches of dinner rolls. So, if one batch makes 15 rolls, then 2 batches makes 30 rolls. Therefore, 3 cups of flour produces 30 rolls.

Laura wants to find how much flour she needs to make 12 rolls.

Here's the setup:

Let x be the number of cups of flour needed. Then,

(3 cups of flour)/(30 rolls)=(x cups of flour)/(12 rolls)

This is the set up for all equations involving ratios. The units should be consistent. Notice how I have flour/rolls=flour/rolls.

It is not necessary to solve the equation, but you should to make sure your answer makes sense. By cross-multiplying, we get x=(3*12)/30 or 1.2 cups.

This solution makes sense. Because 3 cups of flour produces 30 rolls, one cup produces 10 rolls. We need slightly more than 1 cup to get 12 rolls.

89

step-by-step explanation:

c.   x=2.4cm

step-by-step explanation:

similar triangles are triangles which have the same shape but not the same size. this means their angle measures are equal but their side lengths are not instead they are proportional. to solve, we will set up a proportion and solve.

a proportion is two equal ratios set equal to each other. we form the ratios by finding corresponding sides (sides which match to each other on both triangles by their position). out ratios will be one side of the small triangle over the corresponding side on the big triangle as shown below:

.

to solve the proportion, we'll cross multiply by multiplying numerator with denominator across the equal sign.