Solution: 

Given that,

24th term is twice the 10th term.

As we know that, to find nth term in an A.P = a + (n – 1)d

a₂₄ = 2(a10)

a + (24 – 1)d = 2(a + (10 – 1)d)

a + 23d = 2(a + 9d)

a + 23d = 2a + 18d

a = 5d …. (1)

Now, the 72nd term can be expressed as:

a₇₂ = a + (72 – 1)d

= a + 71d

= a + 5d + 66d

= a + a + 66d [using (1)]

= 2(a + 33d)

= 2(a + (34 – 1)d)

= 2(a34)

⇒ a₇₂ = 2(a₃₄)

Hence, the 72nd term is twice the 34th term of the given A.P.