Dilation:
The dilation factor is the length of image/preimage = 1.5
Thus
Q'R'/QR=1.5
Q'R'=1.5QR = 1.5 (5 cm) = 7.5 cm
(Edited)
Just plug it into a calculator and you would get 400
A standard trick for finding the rational form of a repeated decimal:

Multiply by an appropriate power of 10 to move one "cycle" of the repeated pattern to the left side of the decimal point:

Now subtract

from this number and we lose the fractional part:

And from here you can solve for

.
Answer:
1200000
Step-by-step explanation:
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