6(x + 3) = 48 solve for x and give me a number form explanation: 1+1=2

Ihonestly don’t understand this at all

The physical fitness of an athlete is often measured by how much oxygen the athlete takes in (which is recorded in milliliters per kilogram, ml/kg). the mean maximum oxygen uptake for elite athletes has been found to be 60 with a standard deviation of 7.2. assume that the distribution is approximately normal.

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