Multply both sides of the equation by 7.

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When the variable is in the numerator of a proportion like this, you can solve it by multiplying by that denominator. That multiplication cancels the denominator and gives you the value of the variable.
In general, you multiply by the reciprocal of the coefficient of x. When that coefficient is 1/7, you multiply by 7/1. Of course, you know that 7/7 = 1 and that x/1 = x.
Answer:
y=6x is the answer
Step-by-step explanation:
We are told that circle C has center (-4, 6) and a radius of 2.
We are told that circle D has center (6, -2) and a radius of 4.
If we move circle C's center ten units to the right and eight units down, the new center would be at (-4 + 10), (6 - 8) = (6, -2). So step 1 in the informal proof checks out - the centers are the same (which is the definition of concentric) and the shifts are right.
Let's look at our circles. Circle C has a radius of 2 and is inside circle D, whose radius is 4. Between Circle C and Circle D, the radii have a 1:2 ratio, as seen below:

If we dilate circle C by a factor of 2, it means we are expanding it and doubling it. Our circle has that 1:2 ratio, and doubling both sides gives us 2:4. The second step checks out.
Translated objects (or those that you shift) can be congruent, and dilated objects are used with similarity (where you stretch and squeeze). The third step checks out.
Thus, the argument is correct and the last choice is best.