What value of n makes the equation 0.3(12 n-16)=0.4(12-3n) true

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Write the rational number in lowest terms 99/-15

The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?