£150, £160,  £170,...........10 years..............20 years.

STEP 1: Identify the first term in the sequence, call this number a.

STEP 2: Calculate the common difference(d) of the sequence.

STEP 3: Find the term position ( n )

[EXAMPLE: 2,4,6,8,10….in AP

First term 2, term position (n) = 1

Second term 4, term position (n) = 2........

......... 30th term, term position (n) = 30.......

STEP 4: Substitute all the values in the arithmetic formula

[FORMULA: Tn = a + (n - 1) d,

where Tn = nth term and a = first term. Here d = common difference, n = term position.]

STEP 5: Solve for unknown value.