Question 1015486
a5+a4+d
23=a1+4d
72=a1+11d
a1=23-4d=72-11d
49=7d;d=7
If a5=23. a1=-5,a2=2,a3=9, and an=-5+(7(n-1)) ANSWER A.
a10=-5+9*7=58  ANSWER B.
268=-5+7(n-1)
273=7n-7
280=7n; n=40th term.ANSWER C.