Ramkali saved Rs 5 in the first week of a year and then increased her weekly savings byRs 1.75.

Here, a = 5, d = 1.75 and a_n = 20.75

We know, a_n = a + (n -1)d

20.75 = 5 + (n – 1)1.75

(n – 1)1.75 = 20.75 – 5

(n – 1)1.75 = 15.75

n – 1 = 15.75/1.75 = 9

n = 10