Step-by-step explanation:

Sol: Given,

First day earning (a)= 3Rs

And he earns double every next day.

To find: The 10th day earning

From given,

Second day earning =2a=b=6=3(2)

2−1

Third day earning =2b=c=12=3(2)

3−1

Fourth day earning =2c=d=24=3(2)

4−1

nth day earning =3(2)

n−1

Thus earning of 10th day will be

10th day earning =3(2)

10−1

=3(2)

9

=153Rs

Therefore 10th day earning will be 1536 Rs