b5=b1q^5-1
b5=b1q^4
b5 10 81
b1= —— = —— / ——- = 90
q^4 9 1
b1 90 3
S5 = ——- = ———- = 90 * —— = 135
1-q 3/3-1/3 2
b5=b1q^5-1
b5=b1q^4
b5 10 81
b1= —— = —— / ——- = 90
q^4 9 1
b1 90 3
S5 = ——- = ———- = 90 * —— = 135
1-q 3/3-1/3 2