Question 857289
an = a + (n - 1)d
4= 2a + d,
19= a + 18d
a = 53/35,   d = 34/35
check
53/35+53/35+34/35
140/35=4
53/35+612/35=665/35
s = 53/35 + (4)34/35+ 53/35 + (5)34/35
s=412/35 =11 27/35