How to simplify the the expression 6n^2-5n^2+7n^2

If jm equals 5x -8 and lm equals 2x -6 which expression represents jl

After the seventh month of a 12-month loan: the numerator is: {(n + 11) + (n + 10) + (n + 9) + (n + 8) + (n + 7) + (n + 6) + (n + 5)} = , and the denominator is: {(n) + (n + 1) + + (n + 11)} = . therefore, the fraction is numerator/denominator (to the nearest tenth) = %

The radius of the earth is two times the radius of the moon. what fraction of the volume of the earth is the volume of the moon?