book Maths Puzzle Numerical Ability

I am supposed to write the following expression as one logarithm.
2logx+ 1/3log(x+2)-4log(x-3)

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Can someone out there help me solve this problem?

The United States emitted 19.5 million t of nitrogen oxides (NO) into the atmosphere in 1987. One metric ton (1 t) equals 1,
GMm[(R+r)-(R-r)]
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2rR

Can't seem to solve this one