The correct question is:

7 times the 7th term of an AP is equal to 11 times the 11th term. Find 18th term of the AP.

Solution:

Let a is the first term and d is the common difference of the AP.

Given, 7 times the 7th term of an AP is equal to 11 times the 11th term

=> 7(a + 6d) = 11(a + 10d)

=> 7a + 42d = 11a + 110d

=> 11a + 110d - 7a - 42d = 0

=> 4a + 68d = 0

=> 4(a + 17d) = 0

=> a + 17d = 0

=> 18th term of AP = 0