The first term of an arithmetic sequence is 2. The sum of the third and the sixth terms is 25. What is the fourth term?
+37159 3rd + 6th term = 25 let x = third term
x + 3d = 25
AND x - 2d= 2 x = 2 + 2d
sub into the first equation
2 + 2d + 3d = 25
5d = 23
d = 23/5
1st + 3d = 4th term
2 + 3 (23/5) = ........
