Answer:
£ 121.57
Explanation:
As given in question,
Total amount inherited by Tim = £1000
He spends each month = 10 % of remaining money
savings reduced each month = 0.9 of remaining amount
So, the amount of money after one month = 0.9 x £1000
amount of money remained after 2 months = 0.9 x 0.9 x £1000
amount of money remained after 3 months = 0.9 x 0.9 x 0.9 x £1000
Hence, the amount of money remained after the n months can be given by,

Hence, amount of money remained after 20 months can be given by,

= £ 121.57
So, the amount of money remained after 20 months will be £ 121.57.