Answer:
12
3 x 4
if its one unit then you just multiply the sides in this case 3 x 4
<span>If the slope of the ppf is same between any two points, it implies that the opportunity costs did not change and they were constant. So the constant slope implies that production possibilities frontier appears to be a straight line with the opportunity costs being constant.</span>
Hi!
Given:

Multiply both sides by 

<em>Notice the sign was flipped. This is because when you multiply or divide by a negative number, you must always flip the sign!</em>
<u>Now, for the graph:</u>
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For < or > signs, it should be an open circle. For
or
signs, it should be closed.
Since
is less than 6, it should go to the left. Since it's a < symbol, it should be open. Therefore your answer is B.
(looks like you were right!!)