The correct option is A 76
Given 5th term and 10th term of an AP are 26 and 51 respectively.
a+4d=26a+9d=51
Solving the above equations, we get
−25=−5d⟹d=5
Plugging in d = 5 in either of above two equations, we get
26=a+4(5)⟹26=a+20⟹a=6
To find the 15th term,
t15=a+(n−1)d⟹t15=6+5(15−1)⟹t15=76.
The 15th term is 76.