If the sum of the first n terms of the arithmetic sequence {an}, {BN} is an, BN, and an / BN = n / 3n-2, then A5 / B5 =?

If the sum of the first n terms of the arithmetic sequence {an}, {BN} is an, BN, and an / BN = n / 3n-2, then A5 / B5 =?

Because a1 + A9 = 2 * A5
A9=9(a1+a9)/2=9*2*a5/2=9*a5 a5=A9/9
Similarly, B9 = 9 * B5, B5 = B9 / 9
a5/b5=(A9/9)/(B9/9)=A9/B9=9/25