Answer: 280
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Step-by-step explanation:
x = number of downloads for standard version
If x is the number of standard version, then 3*x is the number of the high quality versions because there are 3 times as many HQ versions than standard.
2.7*x represents the total size of all the standard versions, 4.5*3x = 13.5x is the total size of the HQ versions. Combined, we have 2.7x+13.5x = 16.2x as the overall size of all the downloads (standard+HQ).
Set this equal to 4536 and solve for x
16.2x = 4536
16.2x/16.2 = 4536/16.2
x = 280