Solution:

10th term = 41

18th term = 73

a + 9 d = 41 ------- (1)

a + 17 d = 73 ------- (2)

Subtracting the second equation from first equation

a + 9 d = 41

a + 17 d = 73

(-) (-) (-)

-------------------

-8 d = -32

d = (-32)/(-8)

d = 4

Substitute d = 4 in the first equation

a + 9 (4) = 41

a + 36 = 41

a = 41 – 36

a = 5

Now we have to find 27th term

tn = a + (n - 1) d

= 5 + (27-1) 4

= 5 + 26 (4)

= 5 + 104

= 109