It's 12 because if you divide 6 by 0.5 you should get 12, so basically use the opposite operation.
Hope that helps!

<h2>
Explanation:</h2>
Hello! Recall you need to write complete questions in order to find exact answers. So in this problem I'll assume the question is:
<em>A number d minus 4 is less than -1</em>
<em />
So it is easy to know that we need to write an inequality here because of the words "less than", which implies that we must use the symbol <. So let's solve this step by step.
Step 1. A number d minus 4.
This statement includes the word "minus", so we need to use the symbol (-). Therefore:

Step 2. A number d minus 4 is less than
As we said above, here we need to use the symbol (<). So:

Step 3. A number d minus 4 is less than -1
Finally, we get:

<h2>Learn more:</h2>
Inequalities: brainly.com/question/9611462
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In the problem, the first equation should be represented like this base on the variable given in the problem:
20p + 9t = 44.4
with that equation, the second equation would is given by this formula, in response with the additional number of paperback and textbook
21p + 14t = 51
to get the system equation in getting the mass of each variable, you should subtract the two equation to simplified the formula.
20p + 9t = 44.4
- 21p + 14t = 51
-------------------------
p + 5t = 6.6 // this is the system equation that could be use in getting the mass of each object
16 dimes = $1.60
<em>12 quarters</em><em> </em>= $3.00