Question : Find the third proportion of P and 12, when 8, P, 16, and 18 are in proportion.

Question : If $9 a+9 b+9 c=81$ and $4 a b+4 b c+4 c a=160$, then what is the value of $6 a^2+6 b^2+6 c^2$?

Question : When P is subtracted from each of the numbers 8, 6, 2 and 9, the numbers so obtained in this order are in proportion. What is the mean proportional between (3P - 6) and (9P - 4)?

Question : The remainder of the term $9+9^2+\ldots+9^{(2 n+1)}$ when divided by 6 is:

Question : What is the value of $\frac{15 \div 5 \times 3-12 \times 12 \div 6+15 \div 5 \times 6}{18 \div 3 \times 5-12 \div 6 \times 5+18 \div 9 \times 5} ?$