Let the first term of two series be a 1, b 1, and the tolerance be d 1, d2, then:

sn = n * a 1+n(n- 1)d 1/2

tn=n*b 1+n(n- 1)d2/2

sn/TN =(2a 1+(n- 1)d 1)/(2b 1+(n- 1)D2)=(7n+ 1)/(n+3)

= & gts22/t22 =(2a 1+2 1d 1)/(2 a2+2 1 D2)=(7 * 22+ 1)/(22+3)= 3 1/5

Once again:

a2+a5+a 17+a22 = 4a 1+42 * d 1

b8+b 10+b 12+b 16 = 4b 1+42 * D2

=》

(a2+a5+a 17+a22)/(b8+b 10+b 12+b 16)

=(4a 1+42d 1)/(4b 1+42d 2)

=(2a 1+2 1d 1)/(2b 1+2 1 D2)

=3 1/5