The first term of an AP is 8. The ratio of d 11th term to the 7th term is 5:8 calculate the common difference
term 11 = a+10d = 8+10d
term 7 = a + 6d = 8+6d
(8+10d)/(8+6d) = 5/8
64 + 80d = 40 + 30d
50d = -24
d = -24/50 = -.48
check:
term 11 = 8 + 10(-.48) = 3.2
term 7 = 8+6(-.48) = 5.12
5.12 : 3.2
= 512 :320
= 8 : 5