Question 838144
S4 = 26 s5= 42 and s6 = 57

S5-S4=T5 
T5=42-26=16

S6-S5=T6
T6= 57-42=14

T5=16, T6=14

T6-T5= = d the common difference

=-2

Tn = a+(n-1)*d

T6= 14

14= a+(6-1)*-2

14=a-10

a=14+10
a=24

a= 24 d=-2

so the series is 24,22,20,18,16,14,12,.......