The correct answer is that the variability is 2.0 times as large.
In the first set, the MAD is 1.2.
In the second set, the MAD is 0.6.
Dividing 1.2 by 0.6 gives us a factor of 2.
Y=4x is the answers because four times three equals 12 so it works out
Solution:
Let x represent a number of calling minutes. According to the problem, we want:

now, putting the similar terms together, we obtain:

this is equivalent to:

now, solving for x, we get:

then, the correct answer for the first question is:
400 minutes is the number of minutes the two plans cost the same
now, for the second question, we can replace the above value (400 minutes) into the following equation:

so that, the correct answer for the second question is:
$55 is the cost when the two plans cost the same