Question 843224
 a =6(a + 4d)
a =6a + 24d

a2 = a + d
a8 = a + 7d
8=2a+8d
4=a+4d
24=6a+24d
a =6a + 24d
a=24
24=144+24d
-120=24d
-5=d
an = a + (n - 1)d
a20 = 24 -5(19)
a20=-71