t is the 3rd term
t + t + 5d = 7 ... 2t + 5d = 7
t + 4d + t + 11d = -3 ... 2t + 15 d = -3
subtracting equations (to eliminate t) ... 10d = -10 ... d = -1
substituting ... 2t + 5(-1) = 7 ...2t = 12 ... t = 6
10th term ... 3rd term plus 7 differences ... 6 + 7(-1) = ?
if the sum of the 3rd and 8th terms of an ap is 7 and the sum of 7th and 14th term is -3 ,find of 10th term
1 answer