The first term of an arithmetic progression is 8. If the tenth term is double the second term, the common difference is...
8 +d is the second term
8+9d is the 10th term and is equal to 2 x (8+d)
8+9d =2(8+d)
8+9d = 16 + 2d
7d = 8
d = 8/7
+36915 
